He needs your help, one way or the other. I would also try putting him in a cage in your garage, or another room in your home. Just cover it well with something plastic, so if he sprays, it is confined. I know this is a huge thing to take on ... but he really needs some TLC. Maybe you could do a search for some no-kill shelters that would take him in ... someone in your area? Some of them may even help with transport in order to help him out. THey may want him at least tested first though! THanks for pitching in for this poor neglected kitty! Good luck!

Kim