Sorry for the rather long response. I have a very strong possibility of being Celiac. Originally I went gluten free for another condition and was desperate to try anything to stop it. I (and others) noticed I started gaining weight (I've been underweight all my life) and my energy returned. After being gluten free for 2 years, I decided I wanted to be tested for Celiac. However, a person must be on gluten for an accurate test, and I was not on gluten, but got tested anyway. I had at least 2 strikes against me: (1) I have the genes (2) I have the blood line. My Dr. told me he had noticed the Irish tend to get it more, and I'm 3/4 Irish. Not to mention all of the GI symptoms that had gone undiagnosed since my teens.
This past spring I decided I wanted an accurate Celiac test, and with dr. approval, was told to go back on gluten for 2 weeks. After 1 1/2 days I lost all my energy and by day 3 the pain returned. So I decided it was not worth it and went back on gluten free. I consider myself Celiac, although I will never know for sure. But I have most/all of the signs. Gluten definitely bothers me.
I also discovered a few years ago that oats bother me, even those labeled gluten free.They are often processed on equipment that handles wheat items too (cross-contamination). My gluten free magazine ("Simply Gluten Free"), recommended I try Purity Protocol oats. They are organic (no pesticides) and grown in fields reserved only for oats and processed on equipment only for oats.
I've tried the enzymatic peptides that are supposed to help if you get accidentally glutened, but it did not work at all.
Gluten can hide in many places (soy sauce, soups, gravies, medicines, even candy). If your daughter is eating cross-contaminated foods (using shared equipment or shared cooking utensils), or eating hidden gluten, it could cause problems. Also there is something called FODMAP. I don't know what it is, but certain foods (like apples) contain items that can cause problems. I have been told by 2 doctors to eat my fruits and veggies cooked. They contain natural estrogen in varying degrees, and I cannot have estrogen. Cooking them kills the estrogen.