I definitely think a lot of Yorkie have sensitive stomach. Mine still throws up bile once in a while but not as often as when he was younger but I don't think it completely stops when they get older. Just make sure their stomach is not empty. I just need to make sure he eats every meal and supper before bed otherwise its bile time in the morning. I have to sit down and watch him eat or play with his food to get him to eat otherwise it is bile time. He can be quite a bugger sometimes so very picky
and when he doesn't want to eat on certain days because the food is not good enough for him, I quickly give him some yogurt..something is better than nothing.
One of my friend's Yorkie is on RC 28 and she is a little overweight eventhough she exercise a lot and doesn't eat much. I definitely think it is the food.