Hi and thanks for this question.
Sorry to hear about this rash
From the information you have provided, it sounds like you were exposed to an substance that caused an allergic reaction
. This generally responds to antihistaminics like chlorphenamine
etc. You may want to try them as they are available OTC.
However, if you shouldn't get relieved within the next days, then you should get consulted for some other no common causes that are not related to what you have described.
Wish you well. Hope you found this helpful
All the best.
Dr. Ditah, MD