Don't feel bad, I've been having the same problem.

I don't wear nylon panties, I've always been wearing cotton panties and if I wear pantyhose I always wear my cotton undies under them.
I think it might have something to do with being on hrt. I noticed it more when I started Spiro. I also started to itch more on my upper thighs and on back of my calfs after having my legs waxed. The hair folicle seems to be more reddish, but it only lasts for about a week. I never had that kind of a problem before Hrt. The Itch in the crotch area, I take care of by washing the area with an all natural mild soap with Tea tree oil in it, it seems to work fine! I would recomend sticking with natural soaps as opposed the commercial brands, that contain chemicals and are more likely to dry out your skin and cause itching,Especialy if you're on a higher dose of Spiro.
Spiro can give you dry skin! Good luck!