It could very well be epididymitis. But consider another physical exam to make sure it is not a hernia. Another doctor may appreciate a hernia that the first one missed. Having an enlarged prostate and stones probably increases your risk of having epididymitis, because they may increase the odds of pathogens being inside your genitourinary tract. The pain of epididymitis getting worse with exercise is common in my experience. The diagnosis of epididymitis is really one of excluding a lot of things, while having a history and physician conistent with epididymitis.