Our Vet Hasn`t Been Able To Help My Dog. He

Our vet hasn`t been able to help my dog. He has no appitite, wants to sleep all the time, seems to be confused, Has pain when I pick him up. Walk very slow and keeps his tail down. Hes been like this for almost 3 months.. Our vet has done all kinds of blood work on him and other test.. He is almost 9 yrs old..