Well let me tell you there are far worse things to have than Celiac Disease. It is an inherited autoimmune disease that has no cure or meds. The only 'cure' is a life long adherence to a gluten free diet. And you have one big plus in that your child is young and therefore you can start her eating gluten free and she will not know the difference.
Use to gluten free food was hard to find and tasted awful. Now it is far easier, some still tastes awful, but MUCH of it is wonderful.
There are plenty of websites dealing with celiac disease and you can most likely find a local support group. Check with your public library as they may even have books about celiac disease in children along with cookbooks to peak through.
If this is celiac disease, she will not outgrow it. But once gluten (found in wheat, rye, oats & barley(malt)) are removed she will blossom.
Let us know what you find out ok?