My 6 year old DD in the last couple of days has started saying some negative things about herself. This is very new as she normally very confident. The other morning she actually said she hates herself as she is smaller than everyone else, that she can't do anything right and mentioned a mistake she made in school, that she wants to be her younger sister. Please any thoughts as it's making me anxious. She started school this year and seems to be getting on okay but she doesn't tell us much.