My Duck Tolling Retriever mix, who has always been super friendly, and very social, has randomly started to show on-leash aggression. It's like it happened over night. We always take her to breweries and outdoor patios with us and she has started to show her teeth, lunge, bark (which she is not vocal at all) and just over all kind of freaking out. She is a very submissive dog so I know she is not trying to play. Does anyone have any recommendations? She goes with us everywhere and I really want to stop this before it gets out of hand!