opinions...

I had a very brief unprotected sex encounter with a woman a month ago. She says she stays aware of anything that happens 'down there' and so on. I also just started working as a dishwasher a month ago to get some college money. I kinda got in the bad habit of wearing the same boxers over and over without washing any of them and one day noticed some irratation. The irriation got worse the next day...then the third day i examined and saw some redness on the left underside rim of the penis. So i purchased regular underwear and have been using some AD ointment and the redness has gone down a great deal and the irritation feeling has disapeared almost entirely. Im just wondering what ya'll think? There was no itching, burning, tingling, or skin elevations and nothing seems to irritate it besides my underwear..i.e i wash it without feeling any irratibility. I know symptoms can vary, im just wondering if i should be concerned, thanks