Can high protein cause the seizures?

No I did not get him from a store, I bought him from someone who had a litter. He had been perfectly fine til 35 days ago. I heard dexter in my kitchen…I thought he was just playing with my cat, but the noise became louder and faster. When I went to check he was laying on his side pounding his face on the floor convulsing, foaming at the mouth, his eyes were looking around all over, while scratching at the floor. It looked like he was trying to run. At first I thought he slipped and broke his back, but when he wouldn’t look/listen to me I knew it was a seizure. I’ve been giving him phenobarb but he’s still had seizures and the vet said that they could do blood work that would be very expensive and it may not even explain why he’s having them.
My boyfriend and I were trying to think of things dexter’s done before they’ve happened…we both smoke and he remembered that dexter chewed up a cig pack before the first seizure and then another one before his latest seizure. I’m not sure if they had cigs in them but regardless it would still have some tobacco in the packs…could that cause seizures? And one more thing…can high protein cause the seizures? He’s only 6months old so he is still on puppy chow which is high in protein and so the treats he loves. I don’t know if any of this will help me find an answer but I’m throwing it out there anyways. Dexter is my baby and I need help! If anyone has an anser/thoughts/ideas please let me know and thank you to the people who have already shared!