Testicular pain and swelling may be caused by trauma, orchitis, testicular cancer and other diseases. 1. Trauma: As male testicles are relatively fragile, when they are hit, squeezed, traumatized, etc., the local tissues are stimulated, and the patients may have symptoms such as swollen testicles and pain. In serious cases, patients may also experience fainting as well as shock. 2. Testiculitis: Virus, bacteria, chlamydia, mycoplasma and other pathogens may cause testicular infection, and patients may have symptoms such as testicular enlargement, pain, high fever, chills, etc., and serious patients may also have nausea and vomiting. 3. Testicular cancer: the cause of testicular cancer is not clear yet, which may be caused by family heredity, cryptorchidism, testicular injury, long-term use of estrogenic drugs and other factors. Patients may have unilateral testicular swelling, heaviness, slight falling sensation, dull pain, accompanied by nausea and other symptoms, which are manifested as testicular pain and swelling. There are many causes of testicular pain and swelling, and patients are advised to go to the hospital in time.