^No official news but gordokaba from H!O attended the concert in question and said
'From what I could see she realized that she became dizzy or something and tried get off stage by herself. Then the staff ran up and caught her right before she was falling down. I'm pretty sure that she didnt hurt herself then. And with passed out -> fainting. She was lying on the side of the stage for like a second before they carried her away and we couldn't see anymore of her.'
and then goes on to say that it was the end of the concert and so if she did recover quickly there was no point in her coming back on.
I have a worry that she may have anemia or something, having previously been told to rest by doctors, this and the fact she's a girl the age she is makes it quite possible(doctors always seem to test me and other friends for it when we're ill). That said, if it is anemia it's not a big deal and is quite fixable ^_^