a food allergy i never knew about...

after two visits to the doctor, about a hundred bucks on meds, one medical certificate... i was told that i have a food allergy. one i never knew about till this morning. so what am i allergic to? to be honest, i don't know, even the doctor didn't know. although he did say it could a common item. shucks n horrors! ok, fine, i just need my voice back. its such a pain to be croaking! sobs...