Suggest Medication For Pain And Itchiness In Penis After Having Unsafe Sex

Hi Doctor, I have had sex with my girlfriend with condoms all the time, except in two instances where she had her period (the 5th day where there's still a little blood). My penis felt weird. I never had this problem for such a long time. It's been almost 3 weeks, my penis feels a slight pain and a slight itchy kinda feeling when I pee or ejaculate. It doesn't always happen, but sometimes when I pee. Now, it seems a bit better. I wonder what my problem is. Please be adviced. Thanks.