I think it sounds more like a confusion or anxiety problem. Not sure how to react to a human crawling on floor, humans are supposed to be alphas. This is a pug, quite different from a WGSD which I'm told have temperament problems. size would be something else. But the vet will probably have some answers to this. meanwhile, I wouldn't be slapping or yelling at the dog, it will only make matters worse and show him that there really is something wrong with this little human.