Id go straight to a specialist for answers. Most regular vets dont have the knowledge base and experiences. Board certfied vet specialist if you have the choice.
My own cat got mites from my fosters. Shed shake her head and scratch a lot in her ear. No signs of mites when I checked. Took her to the vet and found the mites were deep in the ear canal. Two shots of Ivermectin and she was clear.
Your kitty sounds like she has something much more serious going on. Im wouldnt equate mites with the seizures. But Im no expert. Prayers for you that you find answers in time.
With my eyes, they will be seen...With my voice, they will be heard....
With my hands, they will know comfort...With my action, they will be free...
~TNR and Rescue changes lives of animals.~
When the angels are busy God sends rescuers