Testicular cancer is associated with a painless mass or lump inside testicle. It can be a starting of testicular cancer in your case. This should be checked and investigated further for clarification, at the earliest. It can also be hernia or inflammation of that location. But a simple physical examination done by your physician will bring out a lot of information. So it is better to consult with your doctor first. Testicular pain is also associated with an incorrect blood circulation of that area. Blood vessels when get congested will result in painful twists which can cause swelling or lumps. An ultrasound checkup will reveal further details in this case. Anyway, stay cool and calm and follow the medication as suggested by your doctor. Even cancer at its earliest stages can be cured with assured results.