<human>: I had a bump/pimple/something on the shaft of my penis. it was apparent one day. I didnt pop it or use over the counter treatmsnts it has been some weeks.Now its mostly flat and has a black slightly rough appearencre. It was noticable after a period of maybe a month of multiple encounters with one woman.
<bot>: Thanks for asking in Chat Doctor forum In Short:It may be a wartExplanation: As per your history it seems that you may be having a wart on your pence skin with rough appearance and flat structure. With history of intercourse with many partners point towards this.  I suggest you to visit a dermatologist for this and get yourself examined and undergo investigations to rule out other STDs along with this.  Good luck