Methocarbamol
"I was prescribed 750 mg methocarbamol tablets to be taken three times a day for a muscle spasm under my left shoulder blade.  I tried that twice with no relief so I thought I would up it to two pills.  Nothing.  Wide awake, still cramped up, the pain is a 5 out of 10 (compared to child birth).  I might as well have eaten two crackers.  I wonder if the manufacturer forgot the main ingredient."