I completely understand your concern and I hope I am able to help you for the same.
Seems like you have developed lesions of vasculitis
Hope you are not on any drugs, other than the regular iron and folic acid
Even preservatives in canned and outside food can be a cause.
You need assessment by a dermatologist
for confirmation of the diagnosis.
For the mean time, you can just apply plain calamine
Hope it helps
Best wishes for a speedy recovery
Dr Geetika Paul