Purple spot / bruise? on penis

Hi,

About 8 months ago I had unprotected oral sex performed on me and protected vaginal sex. Since then everything was fine. Had several HIV tests, all negative, and a NGU/Gonorrhea/Chlamydia test. Also negative. Well just recently (past two weeks) I had a slight purple spot show up on the crown of my penis. You have to look close but there is a slight discoloration of the skin. What got my attention was that there is also tingeling and some slight pain at the same spot. Could this just be a bruise? Or should I be more worried?

Many Thanks!