Why is My Puppy Suddenly Aggressive?

While most puppies usually hit a "rebellious" stage, this kind of sounds more like he's in pain and wants people to stay away from him. I would take him to the vet just in case. If nothing appears to be wrong, puppy training classes usually teaches you how to handle the rebellious stage. And you need to do something about it quickly. I have a husky/GSD mix as well, and he got big.