More than two months ago and (a week before my period) I engaged in an outercourse/frottage, with a young and healthy looking guy. More specifically we had some grinding without any clothes and without any condom on, no penetration, at most - he poked me with his penis. His sperm normally didn't come in contact with me. I had a quick rinse after the act an it was a one time occurence.
Initially I was worried about pregnancy risk (which I realized from the beginning), although I already had two periods, but the second was unusually scarce. Then it hit me that I could have caught an STI from him. He had 5 partners before me and I can't be sure if he was healthy. Omitting some minor occasional itchiness, I do feel well and everything seemed fine, but I know some STDs are asymptomatic and this risk has never crossed my mind before as I only had 1 healthy partner and didn't plan on being sexually active. It doesn't help that where I live sex (especially premarital) is a taboo and shame topic and I am quite the hypochondriac type.
I'd like to know exactly what STD risks did I expose myself to? Can all of these be asymptomatic? What symptoms should I watch out for? When and by which medium (blood/urine/ etc.) can each be tested? Can all be tested at once? What else should I know on this subject?
Sorry for such an extensive question and thanks a lot!!!