My two cents: Do the blood test, see what that says. If positive, you know what you are dealing with. If negative, do the 14 days gluten free with gluten on day 15 and see what happens. I think that anecdotal evidence is enough in cases like this - if you can see an improvement then she has an issue regardless of what testing shows.

I have been reading a lot lately on diet in relation to behavior and it keeps coming up again and again with neuro issues (ADD,SPD,ASD,gifted) - sugar and gluten. I don't think it is any co-incidence that the prevalence of these disorders has risen as dramatically as the consumption of processed foods (just my personal little crackpot theory though )