A four month old Yorkie having seizures and no hypoglycemia is very concerning. There is a list of things this could be all of which require vet attention. Your pup needs a second opinion. They will likely start with blood work. If you can't get in to see someone else today, then IMO it is best for the pup to go to the ER of a specialty hospital to get this diagnosed.
There is just no way to know if this is a mild issue or something very dangerous without testing. Have you looked into Care Credit?
I'm very sorry about your pup.
