If he's been scratching at the side of his face and whining for a month, he needs to go to a vet. Immediately. The fact that he sleeps a lot and doesn't play as much is not typical of a 2-year old yorkie. I know mine is 4 and hasn't slowed down a bit.
Please get him to the vet to have him evaluated. Meanwhile, try getting him to eat some plain boiled chicken mixed with rice to get something in him. Good luck and please keep us updated.