Small lump on my left testicle please read?

a around 1 month ago i found a small lump on my left testicle i went 2 days later to my doctor and had it checked. he said it was very small the size of a needle head or a small crumb. he said he could not feel or find a m. he felt it was a inflamation or a syst he gave some ainti-inflamitory pills they helped for around 3 weeks or so now the ache is back not pain just a slight ache. there is no blood in semen before he said if comes back he wants a sonogram what do i have to be scared of? im so scared it could be cancer please give any input u may have