Well, I've personally encountered this problem for ie. a swollen, elongated foreskin and red,itchyness which won't go away(at least for the first 4-5hrs after I woke up frm the previous night which I had a session with a girl)
I went to see a doc almost immediately. I showed it to him and he said it was no big deal. Just applied some anti-fungal cream and the swell and itchyness died off within the same day. But there was another oral supplement which the doctor gave me. Probably some Vitamin E booster or something.
Best bet is to go see a doctor, of course. No big deal, bro!
Good luck!