Odd rabbit behavior?why does my rabbit do this?

ok my rabbit nutmeg will take his food bowl with food and turn it upside down,then when i give him food he diggs into it eating big gulps for like 2 seconds and then he shoves it in his hideout then turns it upside down.then he will sit in his litterbox panting and makes wierd noises every once in a while,and he drinks long gulps of water.why does my mini rex do this?