I have a 9 year old who has been going through these same issues for 6 years. We have done test, been from dr to dr...redone test. I even recently had a dr put him back on gluten so she could scope him again. This made him so sick! He lasted 3 days.
Try to take her off gluten. This is hard at first but you have nothing to lose. Try any veggies, fruits, eggs, nuts and meat. Some people also remove dairy. No seasoning unless you apply it at home and make sure it is just spice and no chemicals. Also you need to remove corn and brown rice. My son went gluten free first and got better only to get worse again. There is alot of talk about people who can't handle gluten can't handle corn or rice either. My son has been corn/rice free for 2 weeks now and is a changed child. No more headaches, very little belly pain. Very little vomitting. He is still very skinny but I hope that will change over time. I beleive it will continue to get better as he heals. This may not work for you, but if you are like I was you will try anything!
Let me know if I can help in any way!