Hi SJL - Sorry your poor DD has had such a tough time.

I have Coeliac Disease and as Nickle said, it is important not to cut gluten out of her diet until after all the testing is done. Usually the blood test will be the first thing they will look at, but really a biopsy is the only definitive way of diagnosing Coeliac. (I actually tested negative in the bloods but a definite positive in the biopsy). Yes, dairy intollerance is more common in people with Coeliac. As is the chance of developing other auto immune diseases such as Type 1 diabetes and Thyroid problems. It may not happen - just something to watch out for. I developed type 1 diabetes last year after being diagnosed with Coeliac for two years.

Eating a strict gluten free diet is the only option and it can be hard. Everything I buy I have to check. Things like meal bases, sauces, vegemite, vinegar etc all can have hidden gluten. Eating out is becoming easier but I find some outlets don't understand the inportance of preparing in a gluten free area with gluten free utensils. Even cooking GF bread in a toaster can pose problems with cross contamination from gluten containing bread.

A great resource is the Coeliac Society. If your DD does have Coeliac, she can join and they have a great magazine and other resources such as an ingredient book which lists common ingredients and if they are GF or not, specials and details of meet ups.
There are alot more foods out there and they have improved even over the last few years.

Being 16, it could be hard for her to make the switch. I know that I miss normal bread, but I also know how sick I feel after I eat it and would much prefer not to feel that way!! :-)

Good luck and if you have any questions, please ask away.