Epididymitis is a condition that results when the epididymis, a curved structure that lies behind the testicles, becomes inflamed. The epididymis normally collects and stores sperm made in the testicles. Epididymitis can be caused by a number of things, including sexually transmitted infections (such as chlamydia and gonorrhea), bacteria that can enter the urinary tract, and blockages of the urinary tract. It can also be caused by problems with the immune system or by injuries to the testicles or epididymis. Symptoms of epididymitis include pain and swelling in the scrotum, fever, nausea, and vomiting.