what do you think i have?

[coasterjosh]

a few days ago during work, i was working at starbucks and i started to feel that the tip of my penis was very irritated/sensitive. like if i rubbed it against my boxers too much so it became raw like a rash. i was at the time using boxers that i grabbed from the dirty laundry pile. (i was in a rush to get to work) maybe there was some feces on it that got into my urethra? or maybe i acidently grabbed my brothers boxers and he had something that i contracted? probably not. idk. but, my tip went back to normal in about a day or so, then it turned into a weird feeling when i pee. kinda like burning but not that much. there's no discharge or anything. i've only had sex once in my life (unprotected and didn't cum) and that was 6 years ago. there's no visible redness or anything like that, i can just feel it a little bit when i pee. also, if i press the underside of my penis, i can feel a soft of tenderness, kinda like an itch but not really. me and my current gf dont have sex and believe in abstinence until marriage, i know for a fact she is a virgin although she does give me blowjobs. she's only given a blowjob to one other guy in her life and nothing more. (she was drugged) im worried that i contracted an std/sti from when i had sex 6 years ago.. what can this be?