Painful yet small rash on genital?

Genital rash. A small painful rash, or lesion, on the genitals may be herpes simplex, a viral infection of the skin that is very common. As many as 100 million americans have recurrent herpes infections of the face or genitals. It is acquired the 1st time from another person, by skin to skin contact, but then reoccurs by itself, almost always in the same spot. It can be treated easily with pills or creams, .