Our doggo’s treatment due to fight with larger dog

My dog is a senior dog and he has arthritis, but he was doing perfectly fine until he had a fight with a bigger dog and he lost pretty badly, he lost his confidence and doesn't seem to run as much now because of it, hes going through treatments and is under painkillers for his injuries, but to add on to all this, hes also getting a castration, the vet said it would be best to get it because hes old and it might affect his bladder and all, if we don't remove it, it could cause tumor in the future too. We hope you guys are able to help out because i am a student that just graduated and i sadly am still trying my best to work towards affording this vet sum. Any and every single amount from anyone will mean the world to me and my strong boy, even if you decide not to donate we hope it wouldn’t be too much of a hassle for you to share our story to everyone who sees this i hope you all have a blessed day :)