Sudheer, if you think the treatment from the current Vet is not improving your dog's health then you should change the vet. If ribs are getting predominent then it definetly means your dog is not fine. Usually, if your dog has loose appetite, vets recommend lever tonics. But, if that is not helping your dog then you should seek help from another vet.
I think you should conduct two tests on your dogs: Blood test and stool test. You should then walk up to another Vet who should check these reports and start treatment.