I don't think there is a good test for gluten allergies, other than possibly the Enterolab test. Lots of gluten free people end up using it. Even that one really looks for an intolerance and not an allergy, so I think it could miss some. If you really want to see if gluten is a problem, I think the best way is to eliminate it all for a while and see what happens. I think you have to avoid even traces of it and cross contamination to be sure.
The first time I did it, I took a very casual approach. I ate in restaurants without asking if there was gluten in what I was ordering. I did not eat any obvious gluten, but I didn't worry about tiny amounts. I didn't notice a difference.
After we all tested positive, I took it more seriously and got rid of it all and could tell, in myself, by the first or second day. I would give it a longer trial though if you do it.
Ideally, you should then re-introduce it and see what happens. I have never intentionally done this because it was such a dramatic change that I do not want to go back to feeling that way, if I can help it.