Thanks for your query.Based on the facts that you have posted it appears that you have Staphylococcal Infection
of hair follicle ( BOIL)in pubic area .
Please consult qualified genera surgeon to confirm the diagnosis.
Please take broad spectrum antibiotics along with anti inflammatory medication like Diclofenac
twice daily .
Ensure to clean your genitals and groin with warm water twice daily.
It should get cured with this treatment within a week.
Your present problem is not related to prostatitis
that you had six months back.as such your serum PSA levels are within normal range.