hey doc, I am a 20 year old male and about 2 months ago had unprotected sex. the morning after, while taking a shower,i noticed some red bumps on my penis. they went away 2 days later and now the skin closest to the shaft on the head of my penis is swollen a bit. i also get a tingling sensation in my penis. i have been tested for hiv, gonorrhea, chlamydia, and a UTI with all negative results. got any idea what this might be?