This is a long question... I read this book about a girl that is schizophrenic.
In the book she see a snake in the cafeteria... She tells herself the snake is not real, because no one else is reacting. Then later another kids book lands in the vents. She climbs up to retrieve the book. She sees a snake again and assume it is not real. Until the snakes wounds itself around her.
Is this the same book?