Try mixing in some wet food with his kibble then eventually phasing it out. Or even just a little hot water on his kibble. That's what I do for my puppy. Try also natural yogurt or canned pumpkin and mix it with his kibble. The thing with table scraps is that they don't have the adequate nutrition that he needs. You could also try Orijen if you can find it where you are...it's a new food but it's made with 70% protein sources and 30% fruits and vegetables. It's meaty and very palatable to dogs.

Has your vet done any tests on your dog? Does he have energy or is he lethargic? I think maybe changing vets is the answer!!!