Could this be testicular cancer?

Hi, so let me start with a little bit of background info. I'm 18 now, but when I was 14 or 15 I found two lumps on each of my testicles, around my epididymis on both testicles. These lumps aren't exactely attached to my testical they are more just rooted to my testicles and aren't very hard and don't hurt much when squeezed. Now about two months ago I started having back pain and I though it was just from standing up for 4-5 hours at work. Now about a week ago my testicles have became slightly tender and hurting a little bit, mostly at night. They also seem to hurt more often on days when I masterbait. The lump on my left testicle has became slightly bigger too. I've read online that back pain can be associated with testicular cancer, but I have also read that having testicular cancer in both testicles at the same time in the same place is unlikely. Thank you for your help