In reply to "mocanady"...
Well, first off Yorkie pups should be kept with their Mom's at least for 12-14 weeks (in case you didn't know
) and any pup at 9 weeks should not be out running around (especially outdoors) until they have had all of their puppy shots.
Your pup was probably overstimulated and is suffering the consequences.
Make sure he is eating, drinking, peeing & pooping...pups this young can easily fade...keep nutrical on hand for low blood sugar!