I had a lump on my upper back for several years a while back. It was an actual lump that would move around under the skin when I pressed it. It wasn't a pimple that could be squeezed. It was relatively soft.
I rarely go to doctors but during a bout of bronchitis, I gave in and went to the doctor. I asked about the bump on my upper back. I don't remember what it was, but it wasn't cancerous. It was a type of fat growth if I recalll. He cut it out of me right there in his office. I had stitches and had to go back to later to them removed. He showed me what he cut out. It was a little fat pellet like an Omega 3 pill.
I don't know what your bumps might be but you really should get it checked out. You'll feel better.
All the best.