I am so sorry to hear about your bun. It sure sounds like she was having seizures or some other neuralogical problem.
Rabbits are interesting creatures. We've had four, 2 of them have died on us from hairballs. It's always tragic to lose such a cute little fuzz. We're very vigilent about the diet of our remaining rabbits now.
And all rabbits are very high stress, although I'm sure some breeds are more prone than others. Seems like dwarfs of any kind are more high strung.
I hope you find another one and have better luck. They are truly sweet creatures.