earlier on after masturbation session, i realized i have a small red pimple like lump and what seems to be an ulcer on my penis head. the size of the red pimple is the size of a dot "." while ulcer is around the size of an "o". its not itching, no burning sensation. my sperm discharge is normal greyish colored.
around 2 weeks ago i had a sexual intercourse with a Thai prostitute. she gave me a blow job without condom but during penetration i used condom.
i was frantic and i search online for possible explanation only to find that it may be symptoms of std. i asked friends who almost had a similar problem and he told me that it may actually be a pimple but he said its quite unlikely for pimple to grow on the penis head. i'm going to get my self check first thing tomorrow morning.
now my question is what the most likely disease from the symptom i had describe on top? is it really pimple or its something else.