i think it maybe normal 'puppy stuff', every morning our 2 young collies will lay under the table then all of a sudden they will just get up and tear around the table seemingly playing chase, my daughter is always saying that her Japanese Spitz sometimes has 'spitz' moments when it will rush around like a mad thing (and she is 5 now). give him a kong or something to chew on, and try not to let him get carried away by barking, you seem to be dealing with it ok anyway