you should go to the doctor now?! why havent you already!

The epididymus is NOT hard. It should feel veiny and kind of squishy. If you feel any hard lumps growing anywhere on your testicles, you should get them checked out immediately. Furthermore, the epididymus is present on both testicles, so when you check both, make sure you check to see if both testcles feel the same on the back. The Epididymus should have roughly the same consistency on both testicles.

You could have an infection of your scrotum/testicles/epididymus or it could be something worse like cancer or benign lumps. Nonetheless, it's very important to get them checked. Infection and cancer can spread to other organs quite easily if not treated!