I found the exact same thing you did, feels like a little grain of rice. Anyway when I went to have it checked out, my Dr felt the sides of the testicles and not the top, as that's where she said a lump would form. That was 7 years ago, and the piece of rice is still there today! Hasn't changed size, hasn't moved. I have never heard of a cancer not growing in 3 months. For someone so in touch with their body and the size/shape of things, you would have 100% felt even the slightest change. You are fine.