have you ruled out celiac? regardless, eliminate gluten, dairy, red meat, and highly processed foods. Give her whole foods that are easy to digest; steamed chicken, white fish, steamed veggies, and fruit. get a good probiotic (id go with at least 50 billion cultures).
Western medicine is absolutely awful when it comes to digestive disorders. They pretty much know nothing. I would find a holistic physician or one that practices functional medicine. You need to go the alternative route, cuz your regular doctor wont be able to do anything. All they do is prescribe medicine that isnt going to help, in fact it will probably make things worse. 100% no antibiotics, not in meds, not in food. They completely destroy the gut.
Try this test. First thing in the morning before she eats or drinks anything, have her gather some spit and spit in a clear glass of water. wait 15 minutes and if the spit "grows legs" as in it kind of looks like a jelly fish. its possible that she has a candida (yeast) overgrowth. If this is the case, she needs to be on a low fodmap (google this) diet. on this diet, she will hopefully see some relief in a few weeks.
She gets minor fevers on and of, she sleeps hot, sometimes sweating profusely
she also gets blood shot whites of her eyes and ulcers in her mouth