Welcome to the board.
Like Cyclinglady said, make sure she keeps eating gluten until all celiac disease testing is done. Those celiacs who are gluten-free will eventually produce false negative test results.
Ask for as many tests as you can get:
- ttG IgA and tTG IgG - tissue transglutaminase is the most common test
- DGP IgA and DGP IgG - deaminated gliadin peptides are newer tests that are often better at detecting celiac disease in young children or in early cases.
- EMA IgA endomysial antibodies tend to become positive as the disease progresses
- total serum IgA - a control tests to make sure one is not too low in IA to produce accurate celiac disease test results - 5% of celiacs are IgA deficient
- AGA IgA and AGA IgG - older less reliable anti-gliadin tests that were replaced by the DGP tests
- endoscopic biopsy - 6+ samples taken
If the tests all come back negative, you could always consider going gluten-free to see if she has non-celiac gluten sensitivity (NCGS). Those with NCGS have the same symptoms as those with celiac disease. Give the diet a good 6 months if you can before judging the effectiveness. Don't go gluten-free until testing is done though.
Good luck. I hope she feels better.