hi congrats on your new puppy! you will have to teach the pup to be alone. he will not learn this from him self. give him a large bone to keep him busy in the time that your not there. put him in a crate where he also needs to be when your at home. he shouldn't associate the crate with you leaving. also let him sleep in the crate. beginwith putting him in your bedroom and when thid goes well place him a little further out of the room until he eventually sleeps through the night. it could be that he's afraid that he will be left alone during the night. dogs live in packs and are actually never alone in the wild. your puppy is also very young. 6 weeks is really too early to leave his mother. teathing is something that is not possible at this age. a pup will begin teathing at 16 weeks. never at 6. ithink that your pup is discovering objects with his mouth. this is pretty much the same as babys do.