I started to get (I'm assuming) the same thing, in conjunction with rawness in that area for the past year. I've tried almost everything other than the exfoliant. I never had this problem for the many years I've been riding
I'm having better success with washing the area before and after the ride. Zit cream and neosporin. I had been using baby powder in my shorts during the day and at night when I didn't have flare ups. I started replacing it this week with something called Monkey Butt, which has baby powder and calamine. Also during the ride I'm using Bag Balm to replace standard Chamois creams.
I'm not cured, but it's improved. I rode 4 hours yesterday, and today I can go out again for a short one. However, I was sore yesterday.
I will try exfoliating.