what semms to be the problem now and what do I have to do?

I have sometimes no control over my legs and then I fall down.The last 3 nights I spent walking around between 1hour periods of sleep.Then I wake up with pain in my lower extremities and my back.This is unbearable.My doc gave me Prednisolone and it did not help.I just fell this night again head first on my back-porch.3 weeks ago I fell and cracked my wrist.I had the same problem 3years ago and I fell two times so bad,that I needed stitches on my head twice.than I received the first time Prednisolone and it worked fast.This time nothing seems to help.I had 1981 lower back-surgery,1991 and 1999 cervical fusion and 2000 a large bone-spur removed also in my cervical spine.I am scared,that I end up in a wheel-chair.