What Happened To My Sweetie-Pie?

Somebody must have taken my daughter and switched her with an evil twin. For the last week or so she has been a terror. Very defiant, oppositional and with crying outbursts throughout the entire day. How can this be that we are a month away from three years old and the terrible twos are rearing their ugly heads??? I'm not sure if it is a phase or if she is overtired but something is not right! She had a major meltdown today because I blowdried my hair -I blow dry my hair every morning!!! Do almost three year olds cut teeth? Help!