Our puppy is 11 weeks old, and he is a golden retriever/collie mix. He has been VERY well tempered since we brought him home when he was 8 weeks old. All of a sudden, he has become VERY whiny, and he seems sad, and hyperactive. He's UTD on all of his shots, deworming meds and heartworm pills. He has been fed, has been given plenty of water, and he gets attention from me all day long, since I work from home. I can't think of what would be wrong with him. PLEASE help us! We are so worried! Could he be depressed? He gets SO much attention, love, exercise and healthy discipline...