My dog is acting strangely?

He keeps pawing at his food and water bowl and refuses to eat. We haven't seen him eat in a day, but today we were able to convince him to gnaw on a bone for a while. We've tried to putting all different types of food in his bowl to. He doesn't want to move and we have to call him over and over just so he will get off her pillow. He's a 4 year old mutt that we adopted a couple of years ago.