ER now, back specialist soon as possible. I did about the same thing and called my DR who called in a prescription of Felxaril which eased the pain immediately. He sent me to a back specialist later that week and of course the back is something hard to see what is wrong. He ruled out anything extremely serious and wanted me to learn back exercises from a physical therapist. I do the exercises three times a week and have never wrenched my back again so far. The exercises do work wonders and they are not like regular exercises, more like stretching.