Itchy red scrotum?

[2er222]

I had unprotected sex two days ago with a rather suspect woman. Lets not get into the issues surrounding that, its over.

Well now its two days later and my scrotum and underside of my penis are very red and itch a bit. I was just having sex and I got a weird kind of chaffing feeling.

So whats the deal? I googled and wiki'd this and I got a bunch of random useless information, I'm hoping somebody can give me a quick diagnosis here. I can't recall any STD's that have that syptom, but who knows.

Thanks for your help and for the flames that I'm sure are coming.