There are many black spots behind the buttocks, and there are also black spots. What skin disease is

There are a lot of black spots behind the buttocks, considering that it may be the performance of hair keratosis, followed by folliculitis may also be caused, generally with irregular schedule, improper diet and other factors. Suggestions: you can go to the hospital dermatological examination, if it is folliculitis, can be external erythromycin eye ointment treatment.