I have a 15 year old Chihuahua who has suddenly become a very picky eater. He has gone through some very big changes recently. He recently had a life long mate that passed a few weeks ago, and we moved since, so he is in new surroundings. His appetite doesn't seem to have diminished, as he still begs for scraps and wants to eat anything we're eating, but he's lost interest in the wet dog food that weeks ago he was gobbling down. He is still as active as before. I've started giving him cheese, as it's one of the few things I have that he'll eat, but I know it's not the best for him. Any advice that might help me?