Very good resources.
I lived with an epi dog for 6+ years. She was diagnosed at the age of 15 months. Bloodwork was done to rule out anything else. (get thyroid tested) We then started on a dose of Potassium Bromide. When that didn't control her seizures we added Phenobarbitol.
In August we lost our Maggie to a brain tumour that was diagnosed in April after having seizure type activity. Again, bloodwork was done and came back normal. Because of her age and lack of seizure activity before this time the vet said best guess was a brain tumour.
You can ask to be referred to a specialist. They will offer to do an MRI. In both cases I turned down the MRI because it is very expensive and even if they found something they couldn't do anything to fix it.
Check out those sites. There is a lot to learn and a great support system at work.