How old is he? My Lady is an epileptic so I know quite a bit about the disease.
Epilepsy in a dog under one year is extremely rare. Seizures in a puppy are usually a symptom of a liver shunt, thyroid imbalance, GME or other neurological problem. Seizures are also a sign of distemper.
Your vet will have to do a bile acids test to rule out liver problems and if that is okay, you will probably need to have a spinal tap and other neurological tests done.
If Tucker is very young, his seizures could very well be from hypoglycemia/low blood sugar. Did your vet or breeder suggest this to you? Scroll down the page to find some information on hypoglycemia.
http://www.yorkshire-terrier.com/lacy/medical.htm