I had a friend and her yorkie started having seizures too........the vet asked her is he had hurt himself.......fell off something?? She was not sure what happened, but the yorkie was an active little guy and jumped off everything no matter how high..........so she thought it was a pinched nerve in the neck because her baby would hardly lift his head......anyway, the vet told her that any type of seizure is Neurological in nature. He put the baby on a small dose of Primadone for about 2 weeks and the baby has had no other affects, seizures all gone too,.
SO, we have said prayers for you here at out house and we hope your vet doesn't just give up on your baby......if worse comes to worse, see another vet if yours won't try a seizure medicine.
Take care and keep us posted.