Why does my yorkie make noises like he is trying to hack something up, but nothing EVER comes out?
Have you taken your yorkie to the vet to check if there is anything blocking his bronchioles or trachea? I would think it is very important for your vet to run some tests just to make sure that there is nothing wrong with him.
It could be a reversed sneeze or collapsing trachea, which yorkies are prone to. Please call your vet at first available opportunity to check what is wrong and make sure it is nothing serious!