If the worse comes to the worse and he can't walk again, as long as he is poo'ing and pee-ing you could get him a doggy wheel chair, also do your own version of hydro therapy, get him a doogy life jacket and fill either a largeish swimming pool with water or even the bath and let him paddle about for about ten mins 2x per day increasing to a 20 min sessions.
Lots of massage, work his back legs for him for 5 mins each leg daily and just keep praying.... the fall may have cause some swelling around the spine, or he make well have herniated a disc.
Dog wheel chairs can be custom made here http://www.doggon.com/products/whlchr.html