I feel pain in my left testicle, what could it be? i've tried checking for lumps but nothing unusual yet. can it be testicle cancer?

Infection?: Pain in your testicles is more likely due to an infection than cancer (especially if you don't feel any lumps), even though testicular cancer is more likely in those <40yo than over. However, testicular pain can also be due to torsion or twisting of the testes in such a way as to cut off blood supply (never a good thing). So if pain persists, go see your family doc. Good luck!

Acute scrotum: Scrotal testicular pain may be anything from a benign inflammation to an infection or torsion or even a tumor. Must be seen right away.