You are in Chicago! There are 24 hour Emergency vets there, so it is never too late at night to take your puppy in. No reason to wait until morning when it would be too late to save the puppy.
Chicago Veterinary Emergency Services - Now Providing Chicago With Emergency Veterinary Care 24 Hours A Day, 7 Days A Week!
Yorkies can go down so fast with diarrhea, as you should know just from reading this forum.