My daughter had the same problem w/ passing out on a more limited basis. They did not find out what was wrong either. But in your daughter's case, it sounds suspiciously like some kind of seizure disorder. Especially since she is so tired all day and shakes & cries while it is happening. Have they investigated this idea? Keep pushing, asking questions. Medicine, I have come to find out, is not an exact science and doctor's frequently resort to their best educated guess. Good luck.