About 11 weeks ago I had protected sex and protected oral with someone whose sexual history I'm not familiar with. Couples of weeks later, I developed this (see photo here: http://www.photobox.co.uk/my/photo?album_id=3486944928&photo_id=20770514729#20770514729).
I tested for syphilis at 10.5 weeks (both VDRL and TPHA/TPPA) and they came back negative. I also tested for HIV with a combo test at 10.5 weeks and it came back negative as well. I tested for Gono, Chlamydia etc. earlier (around 3 weeks post exposure) and they are all negative?
Could this ulcer be STD-related? What does it look like, doctors? Does it look like a chancre, a wart? Signs of HPV/herpes? Could it be something else?