I'm very worried?

I got done takin a shower and gave myself a testicular exam since everything was warm and loose. I found a small bump on the right testicle. The bump was small, and I don't remember ever feeling it there. It's on the back, where the epididymis is. The bump is hard and about the size of a grain. I didn't feel anything on my left testicle like that. I'm seeing my doctor in a few weeks, but with this change of events, i don't know if I should wait. I'm freaking out right now because I don't know if it's testicular cancer.
I'm very worried?
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