Dog is very sick!! please help!!?

Get a second opinion! Arthritis cannot travel for one thing and for the second it doesn't travel that quickly!!! It takes years for it to effect joints etc and so i think the original diagnosis is very, very wrong! I believe your dog has been mis-diagnosed and has been given the wrong drugs over time and thats whats shutting his system down. Take him off all tablets, all his other drugs and start him on a diet of fresh veg ( raw ), fresh meat ( cooked, esp: chicken ) a protein drink such as Complan or Build-Up if he'll drink it and some simple painkillers prescribed or allowed by the vet - please ask the vet on this one otherwise you could do terrible damage to his stomach. Every night - lay him down and mage his limbs and spine with Voltarol Gel, make his back legs especially cycle as if he's on a bike, it'll help with stiffness and pain! Always get a vets say-so on drugs meant for us please, its important but do change your dogs diet, its vital! Best of luck to you both - and if your dog recovers - sue the vet!!! Take care.