Hi I have a 12 mos old 1/2 American 1/2 English lab. Lately when she doesn’t get her way like if I need to leave the park and she doesn’t want to or if I won’t let her play with a dog she jumps and nips me and won’t stop. It’s bad she nips and tears me clothes. Otherwise she is a very sweet and submissive girl. I really need help. This is bad bad it hurts.