[newmommy]

Ok.. well first and foremost I would bring him to the vet. yorkies are so small they can become dehydrated or have low blood sugar and become critical very quickly.
I would pull his food. You can feed him nothing but a bland diet... which is boiled chicken and rice for like 3 days then slowly add regular food back in. However he may need medications to coat the stomach and fluids given by the vet... hope this helps!