I'd find a friendly local vet... most seem better than doctors at fixing stuff.
At the very least they might be able to sort you out with some ketamine.

You might end up in some weird sling dangling from a local stable roof, but hey if it fixes your back...

Did you think on about the crank system that somebody was going on about in a previous post?
You know the medieval crossbow type, maybe something you could hook onto the butt end and crank the bowstring tight.
Slow I know but if it still enables you to function...
AND maybe you could build or have built a ducks foot type crossbow that fires say four bolts at once instead of one to up your firepower??
easy enough to do me thinks.
I tried to be normal once.... Worst two minutes of my life...