Hi, I can understand your concern for 3 mm size spot around urethra of penis. You have not told us your age and history of unprotected sexual intercourse ind its time duration. A close picture with good resolution or a close physical examination is necessary to give you proper diagnosis. Even then based on your history it can be : Simple patch of skin with dryness or Molluscum contagiosum or a Viral warts. For time being period you can apply antibiotic cream such as fucidin or mupirocin and take pain killer tablets such diclofenac or paracetamol. If it is increasing despite the treatment then meet a dermatologist or any family physician and get a proper treatment without delay. Do not try to even touch or pinch the area as can cause more aggravation of the problem and spread of the infection. Take care.