Oh I am so sorry your puppy was sick. I went through the same thing with my baby so I know what you must be going through. Even though it might not help in every case I do think breeders keeping puppies until atleast 10-12 weeks would help see less of these types of situations. However, I live in South Africa and the accepted age to release yorkies is 8 weeks, so likely I will get my baby that young again :/
I'm just hoping I'll be better prepared then
Good luck with your puppy and I hope she grows from strength to strength