I dont know how long you've had him for, but I brought Gracie home when she was 3 years old. For about a month or two she did not have regular eating habits. Sometimes she would eat her food and other times she wouldn't touch it. After about two months she had no problems and happily eats her food as soon as I put it down. I also switched to Honest Kitchen a few months ago which the girls find much more appetizing than kibble.
Lady (1.5 year old tricolour) & Gracie (4 year old blenheim)
"Happiness is a warm puppy" - Charles M. Schulz