Bump on testicle, is this cancer for sure?

ok so my left testicle a year ago had a hard bb size lump in it attached to the testicle, I went for a ultrasound and it turned out to be a calcium deposit. I was happy but recentll on my right testicle I found a bump about the size of a bb on the backside of it, so now I need another ultrasound. The funny thing about this bump is sometimes I can feel around for like a hour and not find it, then all of a sudden I find it, sometimes It almost feels like its not connected, feels like a half shell...like a peacan shell pressing on my skin and bubles up. I mean its hard, like stone kinda. But its hard to find and im wondering if its connected to my testicle or not, sometimes it feels like its part of the testicle and sometimes it does not. Anyone ever had anything like this? Thanks