Could my rash be an STD?
I've been in a monogamous relationship for three years, and we were both virgins when we first had sex. I know for a fact that she has not had other partners, but I had sex with another woman 3 days ago. The other woman has had 6 other partners, but told me she has been tested and does not have any diseases. She looked completely clean and healthy so I was not very concerned about catching something.
I gave her oral sex, she did the same, and we had intercourse with a condom. Anyhow, a day later I noticed a very severe rash around the base of my scrotum. I had been dry in the same area for a couple of days before the encounter and had been scratching the area a lot, so that could be the cause. However, the skin is literally peeling off in sheets now and the remaining skin is very red. There are no blisters or warts and they are not bleeding or emitting any fluid. I am also not discharging anything or having any pain during urination. When I grab some of the peeled off skin and smell it, it smells very strong, sort of like aged cheese. Sorry, I have no other way of describing it. I can wash the area thoroughly and it will smell and look the same just hours later.
My question is, could this be an STD that I got from my new lover or is it just a rash from scratching the area excessively?