Lily was doing fantastic on the leash until she turned 5 months. It was like a light switch. She is trying to run ahead of me, pulling to the side and back. Stopping when she wants. Trying to chase birds. I'm at my wits end. I leave the house determined, but by the time I get back, I am so frustrated. I had been doing the "tug" on the leash and it worked before, but now it seems like that is all I am doing. I want to be able to enjoy my walks with her again, any advice? Also, is it normal for a 5 month old to have a shift in behavior? Its like she is trying to become the pack leader or feels like she already is one. Thanks in advance!