After sex or even masturbation, i have this red mark on the head of my penis. its like someone took a sharpie and made a mark. this mark comes a couple days or so afterwards. then its gone within a day. it doesnt hurt, itch or anything. it isn't bumpy or anything, as i said, its like someone took a pen and made the mark...not sure what it is..not sure how to make an appointment to have it checkout either..unless i masturbate first and then make an appt for a couple days later...any ideas?