
This is not surprising, Eclampsia was the worry from the start when you mentioned shaking.
Bitch should continue to feed the pups but should have daily supplements of Calo Cal D (a specialy easily absorbed supplement) throughout lactation.
I would start the pups on weaning at around 18 days, or as soon as they show any interest in Mums food. Once they are eating well the drain on Mum will be less.
The second Vet sounds like they know more about breeding and rearing.