Thank You For Your Time And Confidentiality. I'm A Freshman

Thank you for your time and confidentiality. I'm a freshman in college and I had sex with a girl last night without wearing a condom. This morning I noticed what looks almost like bruising or darkened capillaries around the (for lack of a better term) peeing hole. I'm extremely worried and the health services on my campus are closed Saturday and sunday. I wouldn't have thought that symptoms of an STD would show in 15 hours so I don't know what to think. I considered whether or not it could be an abrasion from the friction of having intercourse but the discoloration doesn't look like what I thought that would cause. it is about 1-2 centimeters in diameter and is purple/dark pink in contrast with my flesh color and looks as though it . I'm seeing a doctor tomorrow to get it looked at but in the meantime is there anything I could do to help myself (cream, baby powder, Neosporin (probably not))