Urethritis or inflammation of the urethra (the tube running through your dick) can be caused by other pathogens apart from gonococci und chlamydia. You mainly notice urethritis by a burning sensation when you pee. Get it treated by the doctor. With the right medication it's no problem. Otherwise the inflammation can spread to the prostate gland, the balls and the kidneys.

Because it's not difficult for the agents causing urethritis to get into the urethra, this is one of the commonest unwanted side-effects of sex. You can protect yourself effectively by always using condoms when fucking (whether in the vagina or in the arse) or having a blowjob, and by being careful about cleanliness.