Hello, welcome to MedHelp and the forum. Here is an overview of epididymitis https://www.webmd.com/men/what-is-epididymitis#1. It is not uncommon.
There should be no reason why you can't exercise while taking antibiotics as long as you are comfortable enough to do so. You can always check in with your doctor and I would go slow getting back to it and stop if anything causes pain. You can also take an over the counter anti inflammatory for pain and swelling (such as ibuprofen). We wish you the best.