my yellow lab is a 10 week old female. i got her from a reputable breeder. i met both of her parents. here is the problem. sometimes she is sweet and playful, listens to commands, sit, down, stay....other times she will attack us...biting (breaking skin), bark at us, show her teeth, growl at us....we try to stop her, yell or hold her down but she just continues until we finally have to put her outside..please help....we love her and don't want her to keep attacking us!!!!