Is it possible to have an STD rash without it affecting your penis?

I have a bunch of weird red bumps on the upper leg thigh, but I don’t have anything on my penis. Is it possible to get an STD that doesn’t affect your genitals but your legs?

FYI, I haven’t had sexual risk events since November 25 2012.

I’d like to point out that it’s not a shaving rash (haven’t shaved there) and it has been there for about a week or more.