Daughters strange fainting episodes

Hello,
My daughter four years ago, while i was doing her hair at the age of 12, had her head down so i could work at the nape of her neck, she started to lean forward and the fell towards me.  she was unresponsive and i kept calling her name.  She came to and started to shake, her eyes were fully dialated and she said she couldn't see.  we rushed her to emergency and they ran an ekg and CT scan and both returned normal.  we stayed in the hospital for three days  in the childrens ward and she also had an EEG, which came back inconclusive.  She was weak and dizzy and the nuerologist said if it continues to follow up with her normal doctor.  So for three years we monitored her dizziness and encouraged her not too push too hard.  the ultimate thought by the doctors was that she at the time was growing at such a rate her body couldn't keep up and caused her to shut down.

A year ago she was standing at a friends getting her hair cut and her head again was down.  she said "mom, i don't feel well.' i told her to sit and she sat.  within 30 seconds she went limp and started to shake.  the last thing she remebers is me telling her to sit down.  She woke up on the couch.  I made an appointment and took her to the doctor.  Another EEG was scheduled, this time an extensive one.  Again came up with nothing.  So we are now doing what we were doing before....just monitoring....and being cautious.  when she feels like one may be coming on, she lays down.  The doctor said something about when her head is lowered she may be cutting off oxygen and/or blood supply, but to me that doeesn't feel like a real answer.  

I read your comment and it sounded so similar to my duaghter, I felt i had to relate my story to you.  if you have come up with anything, please let us know.