My daughter is 15 and was diagnosed in March of this year. For her, her reaction is immediate, she throws up when she is glutened. I give my children Papaya enzymes (from Walmart in green bottle/yellow cap by Spring Valley--they taste the best) it seems to help with the stomach aches. It is a digestive enzyme. I know what you mean "she gets very agitated...
Hello Katie, I have a daughter named Jessica who is also 15 and just found out in March '12 that she has Celiac...I have to warn you she feels she needs no support groups and such, but I think it would be good for her to have someone she can confide in!!!! She too is the only one in our family who has it. Please reach out to her.