There are two reasons for testicular swelling and pain after ejaculation: 1. It may be due to strong spasms and contractions of the testicles and longer intercourse, resulting in testicular swelling and pain. 2. There may be prostatitis or vas deferens dysplasia. When ejaculating, because of the strong spasm and contraction of these parts, the prostate gland is congested and edematous, and the onset of prostatitis causes pain to radiate into the testicles. It is recommended to have regular sexual intercourse and usually drink more water and urinate more. You can have your prostate fluid tested to see if there is inflammation within the prostate. If there is inflammation, you should have an effective treatment for prostatitis. You should not live long, do not stay up late, and eat less spicy and stimulating food.