My 15 Year Old Daughter Has Had Stomach Issues For

My 15 year old daughter has had stomach issues for a couple of years. This past 6 months it's gotten severe. Severe diarrhea, bloated, doesn't eat in the morning because she feels full and eating then makes her nauseous. She's had blood work fecal work urine work and a biopsy done on her intestines. Everything is fine. She did get braces on 2 years ago. Could the braces be affecting her?