I have a feeling of heaviness in my testicles, I have searched multiple times for a lump but failed. What should a lump on the testicle feel like, should it be hard or soft but firm? I'm really worried because I have googled symptoms of testicular cancer which stated there could be lower back pain. So far I have only experienced heaviness in the testicles and lower back pain which went away after 1 day, though the heaviness still exist but is less noticeable. Should I be worried? Is it possible to have testicular cancer but have no lumps on testicles?

P.S. I was doing some exercises (squats) 2 days before I got the back pain so I dont know if that could be a cause.