Three years ago, my vet recommended Frontline Plus. Put the chemical on the skin between shoulders once a month. It works. He never has had a flea or tick or anything else.
The last two years he has suffered from maybe three seizures a year, about a month apart. Vet prescribed phenobarbital.
On the news yesterday, people were being warned that these chemicals have caused the deaths of some cats and dogs. I am really alarmed and concerned that to prevent the fleas and ticks to save him from Lyme disease, the side effests might be seizures.
He has not had a seizure all winter. The last application of frontline was Sept. I think there are side effects from any drug. Going to be asking many questions to my vet before this spring bug season starts.

I would definetly discontinue using it. Your dog may be allergic. Your right for being concerned. Your Vet can recommend other products to try.

I hope thats it. Easy fix. Pheno is a downer and undoubtedly robbing your dog of some of his energy.