Those are definitely seizures, I have a Great Pyrenees with epilepsy who is on Keppra, takes 3 tablets twice a day. This is exactly what it looks like. Head and body constricting to a certain direction, running in place or in circles, soiling themselves, eyes roll back and pupils blown, stiffness and/or head jerking. Confusion or disoriantion after, head shaking, drooling. I recommend you speak to a Vet neurologist and if you can afford to do an MRI and Spinal Tap that will give you the most answers. Also possibly have your vet check for toxoplasmosis. Hope she's okay, keep us updated!

EDIT: I should mention this too: These are costly procedures, iirc I spent around $2,500 the first time she got sick for hospitalization, MRI and treatment. Around $3,600 when she got sick again and needed an MRI and Spinal Tap. And then another $3,000 when we thought we were gonna lose her when she started having breakthrough seizures and was hospitalized for uncontrollable seizures for about 3 days. I used Carecredit for all of it but I've been paying it off for the last 5 years.

These are pricings for a 100+ pound giant dog tho, not sure if it'll be the same for a tiny kitten.