95 Quest Shaking Problem

I've had my 95 quest for almost ten years and it's been great untill this year. I've never had to change the parts in the van except for brake pads. Well My car is making a rotten egg smell from the exhaust and the car shakes constanly when i drive it, and in all gears. I dunno what the problem is, I'm guessing it might be the Caytalic converter and when i put my hand nice to the muffler pipe, the air comming out of is making the same rythem and i can feel it on my hands. I also thought that it maybe my engine, maybe part of the engine isn't responding. Please Help!