I have a shih tzu named gizmo Hes usually always! Happy and acting like a nut ?

[PandaPaws]

But now he doesn't want to do anything :[ what's wrong with him??

 

[sarahkate]

This may sound strange but I'm a dog groomer and see a lot of shih tzus have a room in-between his pads as the hair gets matted under there and can be quite painful like walking with a stone in there shoe.

 

[KristyHead]

Well, How old is he? Is he having trouble with eating and drinking? If yes you need to take him to a veterinarian asap.
~ Dr. Head

 

[Likewise]

Even the craziest of all dogs tire out eventually, though it is possible he may be sick or injured. Keep a close eye on him for the next day or two, and if he continues not acting like himself, take him to the vet.

 

[Taylor]

their are a lot of possibilities to what could be wrong. your best bet would be to take him to the vet