What Causes Painful And Swollen Testicle After Ejaculating?

Hello, I am a 29 years old male. I am having a pain in right testicle and a little swelling. However there is no puss discharge or any redness in the testes. The pain occurs usually after sexual activity or ejaculation. The pain extends to the legs and hips and remains for around 2 days and then disappears. The pain also starts when i do any physical activity like running. Also there is a constant heaviness in the right testicle. Moreover the right testicle hangs a little upper than the left one. All this started around 8 months earlier and then i consulted a doctor who gave me some antibiotics and painkiller but the relief was temporary. Nothing abnormal was detected in the Ultrasound. But i can feel that everything is not normal because pain is quiet prominent (Not unbearable though). I feel better when I lie down with the hips little upper than the body. Kindly help.