Testicle swalling and pain

You can take him to the hospital or just call your family doctor or a urologist (if your insurance doesn't require a referral). He may have a hydrocele which is a fluid-filled sack along the spermatic cord within the scrotum (although these are ususally painles). Or he could have an epididymitis which is inflammation of the epididymis (a curved structure at the back of the testicle in which sperm matures and is stored). This condition may be mildly to very painful, and the scrotum (sac containing the testicles) may become red, warm and swollen. Infection is the most common cause. In sexually active men, Chlamydia trachomatis is the most frequent causative microbe, followed by E. coli and Neisseria gonorrhoeae. Another cause is sterile reflux of urine through the ejaculatory ducts. And in rare cases, UTI (urinary tract infection).
Another possibility is testicular torsion where the spermatic cord that provides the blood supply to a testicle is twisted, cutting off the blood supply, often causing orchalgia (chronic pain of the testicles or scrotum that typically lasts for more than three months). Prolonged testicular torsion will result in the death of the testicle and surrounding tissues. Two risk factors are trauma and strenuous physical activity. If you think this may be the case, take him to the ER. Testicular torsion is a medical emergency that needs immediate treatment. If treated within 6 hours, there is nearly a 100% chance of saving the testicle. Within 12 hours this rate decreases to 70%, within 24 hours is 20%, and after 24 hours the rate approaches 0. (eMedicineHealth) Once the testicle is dead it must be removed to prevent gangrenous infection.
The other possible problem could be an inguinal hernia which are protrusions of abdominal cavity contents through the inguinal canal. The inguinal canal is a passage in the anterior (toward the front of the body) abdominal wall which in men conveys the spermatic cord (and in women the round ligament). There are two types of inguinal hernia, direct and indirect. Direct inguinal hernias occur when abdominal contents herniate through a weak point in the fascia (uninterrupted, three-dimensional web of tissue) of the abdominal wall and into the inguinal canal. Indirect inguinal hernias occur when abdominal contents protrude through the deep inguinal ring; this is ultimately caused by failure of embryonic closure of the internal inguinal ring.
So if he can't get in to see a doctor today, take him to the ER, unless like I said, evidence points to a possible testicular torsion, then just take him directly to the ER. Keep me posted, Susu