Help me save my big man Bronson

I have an 8 year old 125 lb rottweiler named Bronson, and he is in bad shape. He's had a really serious decline in the past month that originally stemmed from a fall on the stairs while he was playing. After a week he wasn't able to get up himself, and now he can't even walk and doesn't want to eat. His joints all flaired up suddenly and hes in alot of pain. I've been carrying him anytime he needs to go to the bathroom, taking time off work and taking him to vet and hospital visits for weeks trying to figure out whats going on with him. He's gotten so bad that I've had to admit him to the ER since he won't eat, drink or move at all. I've gotten him x-rays, blood work, CT scans and we can't figure out what's going on with him. I have pet insurance and the annual cap of $4,000 has already been hit. I'm trying to get some money back so I can continue getting him tests and all the help I can. Anything helps, I'm trying to recover what my insurance won't pay out so I can pay for more medical care and find out whats going on with him.

Update: They found fluid in his abdomen, he is septic and had to under go emergency surgery, he survived the night but its still very touch and go I am getting him all the help I can so he does not go into cardiac arrest.

After outside donations and some help with insurance thankfully I have got it amount down to $6,125.