^ i have no idea what a discal bar is though 
Discal bar: it can happen to stressed & tensed up long distance, truck drivers, hunched over the wheel with permanent A/C blowing around them. I had sat hunched & tensed up, fault finding in a Control Panel, with cold air conditioning blowing for several hours, then I drove back to the UK with A/C blowing for another 15 hours, shoulder muscles go into spasms, and can get "locked".
Somehow a disc in the spine becomes lopsided, balloons out one side and presses on some nerves, you cannot stand or sit straight, very painful, same side arm & hand gets "tingly" etc, until the "balloon" subsides naturally over several weeks.