Is my pet rabbit dying?

He is about 6 years old. He is breathing very slowly and doesn't move AT ALL. He almost seems paralyzed. He doesn't blink, doesn't look at anything, doesn't sniff anything...nothing at all. Sometimes, in response to touch, he seems to have a spasm or convuslsion, but then back to being completely still. He has not eaten or drank anything for about a day but he seemed perfectly fine yesterday. His teeth are growing very long though. I am scared to pick him up because I am afraid that he will die right in my arms. What should I do?!