Red painless rash on penis. Help identify?

A few weeks ago after sex with my girlfriend I started noticing a rash forming. It is painless and it does not itch. It’s been around for about a month. I don’t know if it’s relavent but her vagina smells quite strong and not in a good way. I’m going to post a picture. Any advice would be appreciated.   In certain lights and when my penis has water on it this is barely visible. 

Is it possible to post a picture on this forum?

You should upload your photo.

She might have a mild yeast infection and you should avoid having unprotected sex until she gets a Pap test.