Hurt my lower back, does anyone know what this can be?

I have never had back problems in my life and the other day I was shaving my legs and I put my leg on the rim of the bathtub and bent down to shave, everything was ok till I stood up. When I stood up straight after bending forward I fell to the ground and could not get back up. I had to go to the ER and when I got there they did a catscan and said all was fine but I was in such pain I couldent sit down at all so I stood for 9 hours untill they gave me morphine! The hospital that I went to is very close to my house but its a bad hospital and am worried its more then a pulled mussle. (The hospital has misdiagnosed me several times once I had pheumonia and they said I had bronchitis) Im taking Vicidan now but my lower back and still hurt badly. I used to go to the gym everyday and now I cant and I wonder when or if I can go back. Im so worried. Anyone know what this pain might be if not a disk? And does a pulled mussle hurt so bad you need morphine and cant even sit at all?