See a doctor. It sounds as though the area may be infected and therefore need advanced treatment.
See a Doctor. Just yesterday a patient came in to see me for a "blister". It was not a blister it was a cyst that needed drained, else risk infection and serious consequences. This involves a procedure that should be done in a very clean to sterile environment.
Cover and TAO. Triple antibiotic ointment and a bandage to let it heal.