Having been in the same situation before, I'd have to tell you to consider komodoman and jeff black's advices BUT, if you don't feel like taking a chance, just go to the doctor.
I've had that happen to me twice in the past. I noticed it when I was j/o, but didn't feel any pain, just a slight discomfort when ejaculating. I waited a couple of days and then j/o again to see if it had stopped and it hadn't. So I went to the doctor and it turned out I had got an "urinal infection" (sorry, don't know how to say it in English). After a few days taking the prescribed pills all was back to normal.
So, don't freak out, but if you feel somewhat scared just go to the doctor. It is better to go there and find out that it is nothing serious than doing nothing and ending up with a rotten dick that will eventually fall, leaving you with some parts missing =P