Flesh/Dark coloured area on penis head with white ring

[MrMe1]

Around 4 months ago i recieved unprotected oral sex from somone whose sexual history im unaware off. This lasted id say 20-30 seconds. After 6 weeks due to anxiety i got tested for STDS and all came back clear. However i have noticed a dark area which is smooth with a white border. Very small on rim of penis head. What could this be?

[purple1234567]

I would just go get checked out from your doctor- sounds like it's not anything STD related, but a doctor will know best what you are seeing.  

[MrMe1]

Im a pakistani male so my penis is a little dark coloured. So the "dark area" is almost very similar to my penis colour but has a little white border/ring round it