Back Spasm

Anyone out there know how long back spasms take to heal? I slipped an fell on the top step of my apartment building's front steps one icy morning a little more than a week ago. I landed a few steps down and felt a massive surge of pain shoot from the lower, left quarter of my back that froze me in place for at least thirty seconds. I went to see my doctor and he put me on a muscle relaxant to keep the muscle from acting up again. But man, without the relaxant at night and without taking a couple of ibuprofin during the day, I can hardly sit. Naturally, I work at a desk in a cubicle where I have little opportunity to get up and move throughout the day. My doctor told me to move as much as much as I could and to do dynamic activities, but he also told me not to climb until this passes. Well, I'm still waiting dammit.