in At Will states an employer can fire an employee for (almost) any reason and an employee can quit for same.
i'm sorry you hurt you back jeff. i swear there is no worse pain. and i'm sorry the job went as a consequence.
but you are skilled and willing and can probably do just about anything!! make SURE your back is fully rested and healed up before seeking another job. this could be the Universe telling you something.....like slow down, take it easy, be nice to your back!!!
don't drink over it, for pete's sake.