Our 14 year old cat has had two seizures in her life. One last July 25 and the first one a year or so before that. Last night she had a mild seizure then recovered in about 15 minutes.
This morning she had three within 45 minutes (I called the vet immediately after the second). We went to the vet for a full workup Sunday Emergency no less. He gave her a Depo shot (corticosteroid in case it’s pressure from a mass in the brain) and a prescription for Phenobarbitol anti-convulsant. Diagnosis… possible brain tumor or general decline from Feline HIV or mystery syndrome. All her blood work, urinalysis and motor function tests indicate she is a perfectly healthy elderly cat. Except of course for the mild seizures, the HIV and some mild hyperesthisia which has never amounted to much. Vet thinks it is possible the hyperesthisia could be related to current seizures as we are at a loss for a root cause.
So we come home. I now have a log of half a dozen mild seizures mostly triggered by noises it seems. She is subdued but otherwise comfortable with periods of normalcy. Her litter box is usually down in the basement but we’ve closed the kitty door to the basement (for obvious safety reasons) and put the litter box in front of the door. She is upset that she can’t go hide in the basement.
Now I’m waiting for hubby to get back from the pharmacy with the Phenobarbitol. We will then have to wait for a perky period where we can try administering it with a treat without traumatising the poor little thing. I’m afraid this is the beginning of the end for kitty. It’s so hard to know what to do and when. 
I would recommend if you notice a tonic clonic that she sees a neurologist to get her the most appropriate drug cocktail to control inflammation and seizures.