Thanks for the query.
Probably you have developed a reaction to the drug.
Drug reaction can develop even months after the drug has been started.
The other possibility is vasculitis
You can apply a mild steroid
cream, like hydrocortisone
this may provide you some relief.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
please meet a dermatologist
for final diagnosis