First of all, welcome to YorkieTalk. This is a wonderful place to help you through this - so much information that you can do a search on and so many experienced Yorkie owners and breeders that can give you advice and support. I am very happy to meet you.
I am so sorry to meet you under these circumstances. It really sounds like you are doing what needs to be done and everyone has given you the best advice. Sadly, these little breed dogs have a tendency to go thru hypoglycemia issues when young - it is why it's best they stay with their mama dog until 12 weeks old. They can just go downhill so quickly. (as you witnessed).
I also wanted to add - KUDOS to you!!! You are a fantastic Yorkie Mom!! Look at what you did! You saw something was wrong and you got her to the vet for attention ASAP. You are doing everything the vet has said to do. AND, you are going beyond all of that seeking and searching more answers and help on your own.
I sure hope you stick around here and become an active member of the community. Once you get thru this, just think of all the future Yorkie Moms you will be able to help (with answers to questions like this). Experience is the best teacher. Hang in there! You and your little Layla will get thru this
