Thanks for posting your query to HCM.
AS per the history and your part of examination, the simple problem your boyfriend is having is folliculitis
. This is inflammation of the hair root and oil glands attached to it which appears as red pimple like bumps on any part of body except palms and soles (don't have oil glands). This can occur due to friction or minor trauma during shaving of the area. Now in your case it is possible by rubbing over his pelvic area or your boyfriend might had remoed in recent past with deep shaving or might be simply due to friction of clothes due to heat and humidity. These lesions heals in a period of 7-10 days.
For STD's sounding similar to these is only one possibility of Molluscum contagiosum
characterized by pearly white lesion without redness
and scabbing over it. So the second one seems to be rare possibility. If the lesions reappear then you can check and reassure yourself.
It appears from your query that it is you who is more worried about the problem rather than your boyfriend. So relax yourself and enjoy good relation with your boyfriend.
Have a healthy life.
With best health wishes,
Dr Sanjay K Kanodia