varicocele or epididymis?

Hello,

I've had a varicocele (varicose vein) on my left testicle for a few years now, but I've discussed it all with my urologist. I've now noticed that there's a soft, palpable lump on my right testicle, located at the bottom of my testicle. It feels about the same as a varicocele. I've done a bit of research online and learned about the epididymis. Is it possible to tell the difference between a varicocele and an epididymis without immediately going to a urologist? And does anyone know how quickly a varicocele can spread?

thanks in advance