I'm so sorry. I do know someone with Celiac disease. She is an adult but the disease just started. It's odd how the body changes sometimes. Her treatment is strictly diet based. No wheat in any form, period. It's going to be very rough as wheat is an american staple in almost everything. It's used as filler in a lot of foods. You need to ask the Doc and do some personal research as wheat can be identified by many different names.
I wanted to tell you that I understand what you are feeling regarding your DD. I have two teenage sons. In 2003, my older son started losing weight to the point he started looking sickly. A routine doctors visit sent us down a path to a surgeon and a gastroenterologist. He was diagnosed with Crohn's disease about 4 months later. This is an autoimmune disorder where your immune system attacks the gastrointestinal tract. There is no cure and he will be on meds forever. To make matters worse, almost 12 months to the day, his younger brother started losing weight. He was also diagnosed with Crohn's. It was particularly tough as my sons are the only grandchildren and the second son was diagnosed 4 days before my Dad passed away. It was a tough couple of years. Both a doing well on meds even though I have to be the pill police at times. Boys think they are invincible.
The reason I shared this is that I wanted you to know that things will be okay. An early diagnosis of Celiac is better than a late one. Like Crohn's, it takes some planning in regards to food choices but it's generally a managable illness. However, as a mother, worry comes with the territory.
Hang tough, stay informed and ask lots of questions. Knowledge is power!