My fur baby is dying..

My cat Ozzy is 4 years old and he had a kidney infection for 2 weeks and he wouldn’t eat anything but drink water and sleep. I got him back from the vet yesterday and they told me to force feed him with a syringe. He fights with me to get the thing in his mouth and he’s scratched me and bit me and runs away to hide. I’ve tried to give him tuna, milk, Gatorade, etc. anything that I can find that he used to eat. He’s all skin and bones and I’m afraid that I’m going to have to put him down or come home to find him already gone. He’s my first fur baby and we just moved him in 3 weeks ago. I’m just not sure what I can do to help him cause he refuses anything I try.