i am not a doctor. i had similar problem years ago.

回答: 紧急求助：皮肤严重过敏， 怎么办？ 由 小竹妈 于 2012-06-12 09:21:34

it just happened and doctor cannot find the cause. i recorded what i eat for several weeks and was noot able to link to anything. i had bad cough without any infection as well the same year. i couldnt wear shorts and short sleeves for two summers. i have been fine in the past several years. i would give credit to regular exercise which gives me a chane to sweat and i have a more internally balanced body now..........when your are exhausted or over  stressed your body lost balance and your immune system is triggered and may fight for the wrong cause.........my 2 cents