Do your own testing
This you can test it yourself.
Wear a shirt or something you believe is causing you allergy to see how you feel. Then don't wear that for couple of weeks--make sure u don't wear similar material either. Keep a long of how you feel. Then reuse that shirt to see if same symptoms occur again. If so, you have your answer. Best treatment is obviously avoid such material/clothing. Consult doc. Good luck.