I would check with your local veterinary school. Their hospitals often have studies going on or they have great recommendations for veterinarians who specialize in such things. Some of the best advice we have gotten for our fosters and our own dogs have been from the schools. Our regular vet isn't constantly keeping up on new studies, etc.
Sometimes, you may end up having to correspond with one further away from you for more information. I also look at the journal articles on google scholar for more current information and e-mail the authors directly.
Underlying Causes for Seizures
It may be worth contacting this veterinarian from the University of Tennessee since it appears he has a vested interest in this very topic. I have had to correspond with them on another case before and they are very helpful. I wouldn't go the herbal route until I knew 100% what was going on. Our regular vet has misdiagnosed several things that weren't nearly as common just because he didn't have experience with them.
Good Luck!