Almost exactly a month ago, my cat Dylan (female, 5 years) was sleeping on a chair when she fell out of it, scrambled about with her belly low to the floor and her pupils widely dilated, head turning panicked from side to side for about a minute, then drooled briefly, and then seemed fine. I thought poisoning, because her sister ate a poisoned mouse long ago and acted similarly. But Dylan stopped after a minute and was normal again. I took her to the vet immediately nonetheless, but they found nothing, other than her heart had a slightly odd sound. She was perfectly fine until a moment ago today, when she suddenly seemed to get startled and then, once again, walked around close to the ground, wide pupils scanning the room from side to side with little or no reaction to others, and when she calmed down, she drooled briefly.
She seems fine now. I have checked and it looks nothing like epilepsy or any other seizure I could find video of. It looks like she woke very roughly from a bad dream and had trouble telling what was going on. But it still scares the **** out of me. Does anyone know what it might be?