My advice....
Archie;
We had a Lab-Shepherd mix named Matty and she had "Cluster" seizures. Just the sweetest dog in the world. Our regular vet could not do much, however there was a vet in town that practiced in seizures but our vet thought that he was radical. Her seizures were getting worse and I decided to use the new vet and if that did not work I was going to put her to sleep.
The vet prescribed the following: Taurine - a liquid (hope I spelled that right), Potassium Bromide - liquid and Azium - a pill that reduces pressure on the brain. I weaned her off all the drugs after 3 years and she was seizure free for 10 years and died of old age 3 days before 9-11.
I hope this information is useful to you.
Mike