The possible reasons for this are: first, obstruction of the vas deferens, which causes partial stagnation of semen in the testicles, resulting in increased internal tension and the symptoms of hidden pain. A routine semen examination is needed to determine whether there is a decrease in the number of sperm or a decrease in vitality, and if necessary, a vasectomy is needed to determine whether there is obstruction. Secondly, if there is an infection after ejaculation, it can cause hidden pain in the testicles. Bacteria can enter the testicles and epididymis through the vas deferens, causing local swelling and pain. The symptoms may worsen with the infection, or with prolongation, and are accompanied by an increase in the size of the testicle or a local lump. Routine urine examination and routine semen examination are needed to rule out any infection. Third, if the erection time is too long or the sex time is too long, it may cause congestion and cause transient pain, and the pain can be gradually relieved after ejaculation.