I suddenly broke out with a series of medium sized bumps that actually made a line around the bottom of my buttocks--much like a horseshoe pattern. after several weeks without getting any better, i went to a dermatologist. she looked under a microscope at a scraping but found nothing. basically, she said they didn t know exactly what was causing it (no new fragrances, etc.) but she was going to treat it as an infected hair. i doubted this seriously because of the pattern of the bumps. she gave me a prescription for antibiotics and said if it didn t clear up to return; she would possibly do a biopsy on it. they did get better, but now there is a dark circle where they were and nothing seems to lighten them. any ideas as to what could have caused them and how to rid myself of these ugly brown spots?