Help with medical care for injured stray cat

My name is Diana and for the past 5 years I have been feeding and rescuing stray cats from my neighborhood. I have four kids that are autistic, and I have a lot going on all the time, but I still make time to help the discarded cats that no one wants anymore. I have saved 11 cats and kittens (four adults of which I have kept as my own) with a little assistance of a very small rescue that hasn't been able to help me for the past couple of years due to their own health issues. I now have 6 cats and a dog and money is tight, but I do what I can. Resources are very limited in my area, so I have been paying for food and spays and neuters with very little help. I am not wealthy, and I do this because I refuse to be just another human to fail them. I don't usually ask for help, but I am in a position now where if I don't ask for help, I will end up spending money I really can't afford to. One of my recent new strays is in need of medical care. He had been wounded on his front leg, (first pics are a couple weeks ago when I first saw it) and it's swollen and needs attention, he also appears to have what may be mites or something as he is losing fur in patches and has sores all over him. I was in the middle of trying to help another cat that had been hurt badly at the time that I first noticed the wound and so he didn't get my immediate attention. He has lost a lot of weight. He is very sweet, and he doesn't deserve to suffer like this. All no kill shelters locally are unable to take him, and so my only option would be the county animal shelter, and due to overcrowding, he's likely to be euthanized. He deserves better than that, and I can't bring myself to do that. I had a neighbor that was going to take him to the vet then that fell through. Everyone near me just ignores the cats and so it is left to me. And of course, he also needs to be neutered. He is also a polydactyl, so he has an extra toe on both front paws. I have been through a lot since I first started helping strays, since I get so emotionally invested. When I started, I did not realize how many would need my help. I am hoping to at least get a little help with vet bills for him, not sure what that will even be. I just can't not try to help. These cats have been failed by humans, and I won't be the next one to do so, no matter how many times I am reduced to tears by the condition I find a cat in. I have no friends and don't really know how many people will actually even see this, but thank you for anything you do to help.