Our 8 month old shih Tzu is a mini who is very loving & mellow until about 6:00pm each evening. At that time for much of the evening she barks, "charges" and runs "wildly from us. We say NO & she barks back and lunges. The next morning & until the next evening she is mellow so that the VET & others say you are lucky to have such a good puppy. Any ideas or suggestions.