What Could Skin Abrasions Or Pimples Suggest?

I've been getting little tiny skin abrasions or abscesses that pop up now and then on my arm pit and/or waistline(sometimes I get a random one on my leg). It usually starts as a tiny one on my waist. Then a couple of days later I usually find one on my arm pit area. They seem too look like inflamed hair follicles. I don't shave those areas anymore and I take showers everyday. I'm 18 so I still go to a pediatrician and I've been there three different times in the last 5 months. Every time I go they do a staph test and it comes back negative. The first time I went I was prescribed an oral pill. It cleared up but then eventually I started to see a new one form. I then went back a couple weeks later and was prescribed topical mupirocin cream or ointment. They eventually cleared up but then a couple weeks later they came back AGAIN. I went to the doctor for a third time and they did another swab test for staph and it still came back negative. They just gave me more topical mupirocin cream. I've been using it and they seem to clear up when i get an outbreak. They usually go away but then they come back days later. They're pretty small and they always clear up whether I use the medicine or not. I just want to know if this is a normal teenage thing or something worse like MRSA. These pimple like things are pretty small and they don't really hurt. They just feel slightly itchy when rubbed against something. If you could get back to me that would be great. By the way, All three doctors were different. Thanks for your time.