I Have A Lump On My Spine About The Size

I have a lump on my spine about the size of a silver dollar it's been there for about a year, and appears to be the same size as when i first noticed it. Recently I've been having some minor back pain, but nothing severe. I have IBS and when my colon is acting up I have some minor back pain. Frankly I am territifed. That I might have cancer. What could it be?