If the testicles are swollen and painful after an erection for too long, the possible causes are: 1. Local swelling and pain caused by semen stagnation, after a long period of sexual stimulation or a long erection, if ejaculation or semen discharge does not occur, then semen stagnation within the epididymis will produce a local swelling and pain. The pain can be gradually relieved by touching the testicles or epididymis with a mild swelling or localized pain. 2. Prolonged erection can lead to varicose veins in the spermatic cord, which can cause mild swelling of the testicles or a painful sensation of falling. If you touch it with your hand, you can feel the thickened and tortuous vascular tissue within the scrotum. The actual fact is that you can find a lot of people who are not able to get a lot of money for the actual money.