That's a good question, especially since every doctor that specializes in scoliosis tells me that scoliosis doesn't hurt.
I think it's the pulling on the muscles, tendons, and ligaments. It sends the muscles into spasm, which is VERY painful. I actually get bone pain sometimes, though. It hurts like a broken bone and my spine can't be pressed on AT ALL when it hurts like that. The burning pain you describe sounds like nerve pain. You could have a nerve that gets pinched once in awhile. It seems, at least in my case, that once the nerves are irritated they tend to stay that way for awhile.
Be happy!
We don't know what tomorrow brings,
but we are alive today!