How long do you need to lay on your back after a spinal tap?

I got a lumbar puncture/spinal tap done 3 days ago and have been doing nothing but laying flat on my back. How long are you supposed to lay flat on your back? A few days or just the day of the procedure? Its so uncomfortable having to lay on my back (I'm a side sleeper). Also, I have horrible pain in my lower back and hips, how long is that supposed to last? I've been taking hydrocodone once or twice a day for that pain. Ibuprofen does nothing for me and I'm tired of sleeping!