my dog is acting strangely

My dog awoke from a nap yelping. For a couple hours after he would shake and growl when I would try to touch him. He seems fine now. Should I be concerned?

I would call the vet... this is not normal for a dog to behave like that... good luck!

Definitely vet. Also, more details please. Age, sex and breed of dog. Any recent interations with other animals/objects which may have resulted in injury. Past medical history. Introduction of new food, toys, companions.

You wouldn't ask your MD for a diagnosis without a full medical history. (:) not critisism, just fact) Same goes for dogs, only more so, since they can't talk.