I was looking for an older post and came across your unanswered post.
All the links worked, which was helpful.
You should look into reoccurring irritant folliculitis.
If it is that, you should avoid shaving or other method of
hair removal for a while.
Tight and irritating clothing, synthetic fabrics, pools and spas with harsh chemicals are all out!
A consultation with an experienced dermatologist might be
necessary. S/he may take a swab to diagnose or rule out a bacterial or fungal infection.