Bad catalytic converter?

Been hearing a rattling sound when accelerating at highway speeds along with a sulfur/rotten egg smell now and then. Wondering if my catalytic converter is bad cause the other day I was driving to work and the car struggled to accelerate up a small hill while driving down the road and then it shuddered and turned the cruise control off as well as flashed the cel a few times. I did check codes one was for a misfire, don't remember what the others were but I'll check again later today.