Hello, I Had Sex With A Girl Who Has Another

Hello, I had sex with a girl who has another sexual partner, and about a 2-4 weeks later two spots appears out of no where, in the beginning of my day there was nothing and right before I was about to have sex again i seen the two spots, I waited a week before I had sex again and it seemed to go away mostly and after I had sex with the same girl 2 more spots appears, but the first two spots are fading, I'm not sure if I have anything, the girl says her friend doesn't have anything and neither does she, please give me some information on what it may be.