I started to have this same problem about a yr & 1/2 ago- also only 34 yrs old- couldn't think of what caused it either- moved some furniture & my back ached alittle afterward but this didn't start for awhile afterward w/the really bad pain where I couldn't even sit up if lying down. Dr thought it was a pinched nerve so spent months seeing a chiropractor & then PT. Finally when nothing was working I asked my dr to get an mri for me (already had an xray & nothing really showed). Once the mri came back it showed I had degenerative disc disease which finally made sense. Saw a neurosurgeon & he said PT would do nothing for me. Sent me to a pain management dr since other then fusion surgery nothing would help the problem. The pain mngmt dr has had me on pain meds, muscle relaxers, sleep pills. Had facet joint injections which did nothing to releave the pain. Have tried Yoga, Tai Chi- nothing works. Have been on pain meds now for about 9 mths & had enough- makes the pain go away when you are taking it & I can sleep but if you don't take them (like if you want to have a couple of drinks w/dinner or something) you are back in awful pain. Have appts to see the neurosurgeon again to discuss surgery & also an orthopeadic surgeon for a second opion. My advise would be to get an MRI as soon as possible- I waited at least 6 mths in pain before someone actually found out what it was. Good luck w/everything & hope it turns out better then mine so far.