My last sex was i gave a man one second unprotected oral sex and protected oral sex, no anal sex at all, and i did not use my penis during the sex. the man i had sex did not touch my penis as well. the sex was on 12th Feb. I checked hiv, syphilis, hep A B C, chlamydia, gonorrhoea 4 months after the sex, all came back negative.
However, yesterday i found a pimple （like a whelk）on the bottom of my prepuce, located in the joint between penis and scrotum. it is approximated 0.2 cm in diameter. I dig it broken, it was bleeding a little bit, and now it was scab.
Is this possible a hard chancre, a symptom of syphilis? I am worried about that. or is it possible that the nurse was using used needle when drawing my blood that i caught any STDs? I took my final STDs screening on 11th June, the pimple showed on yesterday.
Please help me everyone, is that syphilis or just a normal folliculitis on prepuce? I ate a lot of spicy food recently.