You must have developed pyoderma i.e. a bacterial skin infection
. It may be furuncle or abscess.
You should seek opinion of a dermatologist
or a physician, because you need antibiotics. If it is abscess and is in advanced stage, it may need incision & drainage by a surgeon.
Meanwhile start NSAIDs like ibuprofen
and also take sitz bath twice daily.
Dr. Ajit Singh Kulhari
MD - Skin & VD