I Fell Out Of A Semi Trailer, Landing Very Hard,

I fell out of a semi trailer, landing very hard, flat on my back. This happened 3 months ago. Xray showed no fractures. However, the pain is intense still. I have a previous back injury from 15 years ago, compression fracture of T7, but now my entire back is the issue. If there's nothing broken, what could be causing all of my pain and limiting everything I do? I was still having some issues with the first injury, now I'm in terrible pain and the work comp doctors don't seem to care about finding out what could actually be wrong. Any input would be appreciated. Thanks!!!