Rooting for Apache. Give him time, he'll get there. I think perhaps your theory of injury was correct. I think you're other rooster or chickens may have injured him.am observing... that Apache is doing AND feeling better and better... He is improving, and fast!
He can now preen his feathers on his back, and he keeps moving all day and trying to stand by himself - and there are progress... SMALL progress, but progress nonetheless.
Wishing you both the best to get through it!