Does her back ripple when she freaks out? Does she try to lick/bite her flanks or her tail when these episodes occur? It coule be feline hyperesthesia syndrome. Of course, you'd have to talk to your vet to rule out other things (like fleas or skin allergies) to know for sure. It's (mostly) found in cats with some kind of Siamese background, and can be treated by doing something as simple as enriching your cats environment, or in more severe cases with anti-anxiety and anti-OCD drugs.
My cat does almost the same thing. His eyes will become dilated and he'll start spinning around, as if some unseen predator is attacking his tail. Then he'll run off and hide briefly, only to emerge as if nothing has happened. He also doesn't like it when you touch him near the base of the tail. He also will become very upset and meow loudly, for no reason for an hour or so on end.
I'm not sure if it's a very common disorder, so I'm not sure if I'm coming out of left field with this. But if you try everything that people suggest and still have problems, then maybe this is something to look into. I know with my cat it started to manifest once in a while when he was about 1.5 years old, and has worsened somewhat over time so that now he has these episodes every other day or so. Good luck.