I Began To Feel Some Pain In One Of My

I began to feel some pain in one of my testicles. Swelling began so I went to er after a couple days. On a scale of 1-5 pain was a 3. No pain during urination or ejaculation and no secretion from the penis or sores/bumps. At er I was asked about my sexual history. Have had the same partner for almost 10 years and we both are regularly tested. They did an ultrasound and gave me a shot in my bum. After waiting a while they came in and prescribed me a 10 day dose of Doxycycline and dismissed me with epididymitis. Said it would kill the infection. I read online that heavy lifting can be a cause of epididymitis. I do heavy lifting at work. Wondering what non sexual activities can cause epididymitis? I'm 30 years old and had an accident about 15 years ago and injured the testicle that recently had pain/swelling. Not sure if this may have to be looked into further? Thanks