Pain next to the testicle may be caused by epididymitis, orchitis, varicocele and other diseases. 1. Epididymitis: Epididymitis may be caused by bacterial infection, sexually transmitted infection, urine reflux, vasectomy and other factors. Patients may have increased and hardened epididymis and scrotal pain, which may be persistent and severe, manifested as pain next to the testicle. 2. Testiculitis: Testiculitis may be caused by sexually transmitted infections, inflammation, pathogen infection and other factors. Symptoms of testicular inflammation are enlargement and pain in the testicles, which can radiate to the groin and lower abdominal region, and some patients may be accompanied by obvious pressure pain, tenderness and other symptoms, which can be manifested as pain next to the testicles. 3. Varicocele: Varicocele may be caused by venous valve insufficiency, venous return obstacle, standing for a long time and other factors. Patients may have symptoms such as scrotal enlargement, swelling, hidden pain, etc. Some patients have pain next to the testicle. There are many causes of pain next to the testicles, and it is recommended that patients go to regular hospitals and undergo relevant examinations, so as to clarify the causes of the disease.