Hello,
Thanks for posting your query,
I believe it could be any kind of
skin rash but I do not think it is as a result of the injection that was done weeks ago. Normally
cortisone will hardly present with such adverse effects and if it was
allergy to the cortisone, then you would probably had to manifest those rashes just a couple of hours to a few days from time of injection.
From the description of rash (even though not complete), you have a skin affection which could be an allergy to something (as your doctor mentioned), infection due to bacteria, fungus, virus etc, or manifestation of a underlying diseases condition. Well if antihistamine +
steroid ointment did not work, it simply means that it might not just be an
allergic reaction and your treatment will necessitate that your doctor identifies the specific cause and treat it first.
Hope this helps and wish you the best