I have a high output ileostomy like yourself and can give you some tips.
1: There is a whole list of foods to avoid that trigger high flow. I'll post that at the end of this post. A nutritionist can also supply the info and more, like doing a blood test.
2: If you're still hooked up to an IV, well, that's going to do it right there. It's putting sugar into your bloodstream to feed you, but when your body has too much sugar (or anything easily converted to sugar like starches), it's going to try to flush it out, thinking the source is the stomach. So there isn't much you can do there but ask the doctor to get you off the IV as soon as possible because you're having high output issues.
3: If you're on solid food, you need to avoid eating too much at one time. I know meals are big and all, but you have to learn to eat small nutritious meals more frequently during the day and only a small pudding cup size here and there after 3 pm. This will allow your body to catch up and not fill your bag up all night long.
4: My routine is when I wake up, I eat nothing. If black syrupy bile is filling the bag, it means I'm hungry and it won't stop until I eat something (applesauce works great) small and wait a bit, and it will stop for a while, letting me remove the bag and take a shower, dry well, and put a new bag on. Then I'll go eat a nutritious breakfast.
5: In the afternoon, I'll eat something like a grilled chicken breast sandwich and water, that's it. Great protein. But always small portions, not more than a sandwich as not to overload the bag. Not too much starch (rice, pasta, wheat, potatoes), almost no caffeine (especially coffee as it makes the burns worse), and fried or overly spicy or salted foods. (Like brined chicken of KFC and rotisserie chicken).
6: Electrolytes are important as well, you can drain your body of these if you're drinking too much water. Here is a link to making your own. However, if you're eating a balanced diet, you should eventually be fine and not need this.
https://health.ucdavis.edu/surgery/documents/ileostomy-hydration.pdf
7: The doctor may put you on Imodium to try to reduce the flow, but it's really not much of a help until you start controlling your diet intake type and amount.
[b]Signs of a clogged stoma.[/b]
No output or only watery output under pressure for a few hours after eating. Could be caused by a covered stoma by improper application of an appliance, typically the hole is cut too small or too much paste. Also could be caused by eating hard food. Seek treatment by an emergency room, remove the appliance if necessary and wait. If clogged, severe pain will eventually appear which hopefully will clear itself. If not, a trip to surgery would be necessary. Unfortunately, very high and frequent output will ensue after clearing for quite some time which will likely make putting on a replacement appliance difficult. Use stool thickening tactics (below). If going to an ER, bring your own ostomy gear and a change of clothes as the hospital likely doesn't carry or doesn't know how.
[b]What is "pancaking?"[/b]
Pancaking occurs when a vacuum in the bag (likely due to a clogged filter) or super thick stool blocks stool from depositing to the bottom of the bag. This can force the bag off and cause leaks. Controlling what one eats and by mixing and consuming stool thickening and stool softening foods at the same time to get a balance.
[b]What is "ballooning?"[/b]
Ballooning occurs when foods eaten produce too much gas and the filter gets clogged (likely due to lying down) and thus forces the bag off and causes leaks.
These two conditions can cause premature bag replacement and leaks which burn the skin. It's better to replace the appliance if there is any continuous stinging pain, don't just live with it. Keep an eye on your ostomy supply and have ample reserves.
I've found that caffeine, in coffee, tea, and even chocolate causes diarrhea and can assist in controlling flow so stool is more liquid. However, coffee makes output very acidic making burns worse. Dried Chinese Crispy Noodles, Cheerios, or applesauce (peeled apples) are the exact opposite, a stool thickening food. By mixing these with other foods one can manipulate their stool output and counter the issues above. Also, the severe thickening helps in cases where one has severe diarrhea and is unable to reattach a new bag due to high flow.
[b]Eating Guide[/b]
Partially copied from my nutritionist's guide. Ileostomy Nutrition Therapy from the Academy of Nutrition and Dietetics. (This handout may be duplicated for client education.)
My recommendation is to see a nutritionist for the full guide as not all can be pasted here.
I've added my own observations to further clarify.
Chew all foods well to the consistency of paste.
[b]Foods That May Cause Blockage (very bad, avoid!)[/b]
Apples, unpeeled (unpeeled and applesauce are excellent thickeners, don't eat the core, chew well)
Bean sprouts
Cabbage, raw
Casing on sausage (inside fine if no tough parts, avoid swallowing if a chunk is felt)
Celery (avoid)
Chinese vegetables (stir-fried crunchy, too hard, need soft veggies with no skins)
Coconut
Coleslaw
Corn (grits also, corn anything doesn't seem to dissolve in the stomach)
Cucumbers (skins bad, inside chewed up good seems okay, no seeds)
Dried fruit, raisins
Grapes
Green peppers (red, yellow also) pureed or very very small seems okay in small amounts
Mushrooms (doesn't dissolve in the stomach) pureed or very very small seems okay in small amounts
Nuts (totally avoid)
Peas (mushy interior okay, like pea soup, skins a problem)
Pickles (skins a problem, inside if chewed up good seems okay, seeds not)
Pineapple (liquid okay, mushy parts fine, hard parts not, tricky)
Popcorn (totally avoid)
Relishes and olives
Salad greens (diarrhea nightmare too)
Seeds and nuts (avoid)
Spinach (doesn't digest, pureed perhaps)
Tough, fibrous meats (for example, steak on grill, well done, tough parts especially)
Vegetable and fruit skins (any avoid)
Whole grains (no grits, oatmeal seems to be okay, Cheerios is an excellent thickener)
[b]Foods That May Cause Gas or Odor[/b]
Alcohol
Apples
Asparagus (stink)
Bananas
Beer
Broccoli (clog hazard)
Brussels sprouts (clog hazard)
Cabbage (clog hazard)
Carbonated beverages
Cauliflower
Cheese, some types
Corn (clog hazard)
Cucumber
Dairy products
Dried beans and peas (clog hazard)
Eggs (don't digest in the stomach)
Fatty foods
Fish (cooked salmon in small portions may not, nor stink)
Grapes
Green pepper (red and yellow also, clog hazard)
Melons
Onions (clog hazard)
Peanuts (clog hazard)
Prunes
Radishes
Turnips
Soda and sipping using straws (drink from glass instead)
Seafood (oh God, does it stink!)
If you're having pancaking issues, a small amount of something above (like having a soda during a meal) could introduce some air into your diet and thus into the bag. Also, by avoiding too much thickening foods by themselves which often contribute to pancaking.
[b]Foods That May Help Relieve Gas and Odor[/b]
Buttermilk
Cranberry juice
Parsley
Yogurt with active cultures (Greek yogurt)
[b]Foods That May Cause Diarrhea (looser or more frequent stool)[/b]
Alcohol (including beer)
Apricots (and stone fruits)
Beans, baked or legumes
Bran
Broccoli
Brussels sprouts
Cabbage
Caffeinated drinks (especially hot)
Chocolate
Corn (in my experience, corn anything doesn't digest in the stomach, just passed through and out, kernels/popcorn will clog)
Fried meats, fish, poultry (KFC, supermarket rotisserie chicken very bad, anything soaked in brine)
Fruit juice: apple, grape, orange (small amount okay)
Fruit: fresh, canned, or dried (small amount okay)
Glucose-free foods containing mannitol or sorbitol
Gum, sugar-free
High-fat foods
High-sugar foods
High salt foods (KFC, supermarket rotisserie chicken)
High seasoned foods (blackened)
Licorice
Milk and dairy foods (small amounts okay)
Nuts or seeds (bad, clog hazard)
Peaches (stone fruit, one rarely okay)
Peas
Plums (stone fruit)
Prune juice or prunes
Soup
Spicy foods
Sugar-free substitutes
Tomatoes
Turnip greens/green leafy vegetables, raw
Wheat/whole grains
Wine
Rice (1/4 cup mixed in food okay), refried beans (1/4 cup okay), pasta (one cup max).
Any foods soaked in brine or fried (rotisserie chicken, Kentucky Fried Chicken, etc.)
[b]Foods That May Help Thicken Stool[/b]
Applesauce (unpeeled apples, no cores)
Bananas
Barley (when OK to have fiber)
Cheese (cheese food may be a clog problem, use real cheese)
Dried Chinese Crispy Noodles (severe thickening, mix with other food that causes diarrhea)
Marshmallows
Oatmeal (when OK to have fiber)
Pasta (sauces may increase symptoms) (in my experience, more than a cup of pasta causes diarrhea)
Peanut butter, creamy only, nuts clog (makes skin oily)
Potatoes, no skin (skin clogs, more than a cup causes diarrhea)
Pretzels (salty may cause more flow water consumption)
Metamucil, mix or crackers (mix in a cup of water and drink before it gels up)
I'm adding to this list based upon experience.