What Could Tender Rashes/bumps On Scrotum Suggest?

Hi i have a teander rash like thing, around the base of my scrotum nearest to my stomach. its on each side.there are little like pimple bumps that i can pop, and they let out a gew . I had it once before, and then me and my GF had sex the other night and it seems irritated. What could it be?