I hope you get some answers soon Ash. I just wanted to add that if you do suspect Coeliac disease, make sure the tests are done before you completely cut out gluten, otherwise she will have to start eating gluten again before the test. Fructose is the other thing to consider, a friend of mine had awful stomach problems for years and that is what they have finally narrowed it down to.

Good luck, I hope it's something that is easily fixed!