Rash/iching bumps

Hello, so heres the story:
  I slept with my girlfriend a few days after she shaved her pubic area, i got 2 or 3 red pimples on my legs, which did what pimples do, were quite small, and about 1 inch apart where her thigh touched mine.  no dramas there.
  1 week later, we slept with eachother again and i got 4 or 5 more pimples, though the first ones had healed.  I also got one on my arm, a bit funny.  I got a bit concerned at this point because the pimple on my arm had a red sore area around it.  After I poped the pimple on my arm (shouldn't have, but did.) the sore area expanded from the size of a quarter to about 8 inches long by 2 inches wide.  It felt very bruised.  two small pimples poped up next to the first about an inch away.  Weird, but it faded in a week or so.  
  A week later, slept together, got a couple more bumps, you get the idea.. though one of the bumps did have a red sore spot around it like on my arm, the red sore spot (slight discoloration only, no inflamed skin) spread to be 1.5 inches by .5 inch, don't have a clue, but hey didn't seem serious.  everything faded quickly.
  one of the recent weeks, (she had been shaving periodically) we spent more time in bed than usual, and i ended up with 20 or so little pimples that were from .5 inches to 1 inch apart.  All of these bumps seem to be at the root of a hair.

[Alan Rockoff, MD]

All I can think of is that the heat and sweat resulting from contact caused folliculitis, or blockage of the pores where the hairs emerge.  I am perplexed by your description of a, "sore area expanded from the size of a quarter to about 8 inches long by 2 inches wide."  I can't imagine what that's about, although it did go away.

If your girlfriend had any sort of skin infection, it would be visible, which I think I can assume it isn't.

My advice is to shower daily with an antibacterial soap, and to apply an antibiotic ointment like bacitracin or neosporin to larger pimples and not to squeeze them.

If symptoms persist, as they say, please call your doctor.

Best.

Dr. Rockoff