What Causes Painless Spherical Shaped Lump On Testicle?

I have a spherical shaped ball on top of my right testicle. It does not hurt or anything but is a size of a small pea. It is near the epidyimis. My testicle is not swollen there is no rash or any change in color I just noticed it a day ago and before that had no feeling. Can you please help can this be cancer I am very worried.