Thanks for query,
The diagnosis of her unconscious spell should be done at that times vital data like Blood sugar level .Pulse & blood pressure reading of that time.
If she had normal blood pressure at that time with low sugar level the possibility of hypoglycemia
is there.Postural Hypotension
may be one of the reason.
The most likely possibility should be syncopal attack as she falls suddenly.
She also needs ENT check up.