Feed your dog top of the range quality god food, i recomend purina pro plan performance if you can get it, has high levels of fat and calcium and will improve your dogs health dramatically, also his coat condition and you will soon notice the diference in him.
also I would get your dog checked by the vet straight away incase there is an underlying problem,
also when was the last time he was wormed? he could just be needing something simple as wormed and onto a better quality food, but if in doubt always see your vet. Hope this helps.
