What does this look like?

It started as what I thought was a big bite, but has stayed persistently itchy for about a week now. I keep absent-mindedly scratching it before catching myself. It's on my left breast right about where my bra sits. I'm going to the doctor tomorrow so I'll have him look at it then, but googling "red circular rash on chest" brings up breast cancer without providing comparison pictures. So I figured I'd ask here.