I Have A Rather Large Lump At The Bottom Of

I have a rather large lump at the bottom of one testicle. It is about 1 cm across, but is irregular in shape. Part of it is a lot firmer than the rest. I feel no pain except if I squeeze it, and even then the pain is mild. The testicle is not swollen. Since I weigh 260 pounds and am considered obese, I might have pinched it a few weeks ago when sitting on the ground. I had a vasectomy 35 years ago. I am 74 years old. I see a urologist twice a year.