A little vague swelling and pain in the abdomen and testicles may be caused by testicular inflammation, kidney stones, prostatitis, varicocele and other factors. 1. Orchitis: it may be related to bacterial or viral infection, which can lead to orchitis, causing localized damage to the testicles, and in serious cases, it may lead to vague swelling and pain in the abdomen and testicles, which may be accompanied by redness, falling and other symptoms. 2. Kidney stone: it may be related to diet, metabolic abnormalities in the body and other factors. When kidney stones are discharged downward, they may get stuck in the lower end of the ureter, which may cause distension and pain in the abdomen and testicles, and may be accompanied by frequent urination, hematuria, difficulty in urination and other symptoms. 3. Prostatitis: Frequent masturbation or poor hygiene may induce prostatitis, which may lead to vague swelling and pain in the abdomen and testicles, accompanied by frequent urination, dysuria and other symptoms. 4. Varicose veins: a vascular disease, resulting in localized obstruction of blood flow to the testicles, may cause symptoms of abdominal and testicular swelling and pain, and in severe cases, may also cause male infertility. To summarize, a vague swelling and pain in the abdomen and testicles that lasts for a long time indicates the existence of abnormalities, and it is recommended to consult a doctor for examination and treatment in a timely manner.