I get a lot of acne on my pelvic region after a lot of intercourse? what can this be?

Not acne!: The lesions are probably not acne. You may have a sexually transmitted infection or infections. It is imperative to see a doctor. Your county public health department may be helpful.

Folliculitis: Sounds like you may have folliculitis. A culture of the area may be helpful as would a biopsy. You may have irritation of the hair follicles there from friction or it could be a viral or bacterial cause. Laser hair removal may be preventative- make sure that your partner is also checked.