Anonymous wrote:My daughter works with rescue dogs and one lab mix was acting like this. It turned out he had a huge prickly burr stuck in his ear. They removed it and he calmed down. Good idea to have a checkup.
The only other thing I wondered from your description was if any of the other dogs have been too aggressive and she's feeling intimidated and defensive. Don't stop socializing her, just watch that it's with friendly socialized dogs. She sounds like a great dog! I have a retriever mix too.

Anonymous wrote:It could be that something is physically wrong and causing her pain or discomfort.
Whenever you notice a sudden change in personality in a dog, it's a good idea to schedule a vet visit.
Basically, dogs don't have a way of saying, "hey, this hurts."
Best of luck.