My Lady is an epileptic so I know more than I would like to about the disease.
First of all, seizures in a dog under one year old are almost always a symptom of another disease, not a disease (epilepsy) itself. Just giving your puppy anti-seizure medication is not a solution. You must find out what is causing the seizures. Also, seizure medication (phenobarbital) damages the liver and if he has liver disease, this will only make things worse.
These are the causes of seizures in puppies with the most common being first:
Anomaly: hydrocephalus.
Inflammatory:
Infectious - Viral: canine distemper; parasitic; bacterial; fungal
Immune mediated
Metabolic:
Hepatic - portosystemic shunt; Autoimmune thyroiditis (early stage: TgAA
positive); Hypoglycemia; Electrolyte disorders
Toxic: Single or combination vaccines; Lead; Drug related; Other exposures
Trauma: Acute; Delayed
Degenerative: Storage disorders
Primary: Idiopathic Epilepsy ("idiopathic" = cause unknown or undetermined) POSSIBLE CAUSES OF SEIZURES BY AGE
Did your puppy have a bile acids test? Simple bloodwork cannot diagnose liver disease. Since Yorkies are 36 times more likely to have a liver shunt than all other breeds combined and seizures are one of the symptoms, he needs a bile acids test.