Your car hit a pothole and there was a loud thump then a bad sewer smell in the car with no leaking or smoke evident so is there something wrong?

The Smell Would Not Indicate Any Trouble. If It Doesn`t Seem To Make A Strange Noise Or Steer Differently It Should Be OK. I Suggest You Have Your Garrage Put It On A Rack & Check It Out. Don`t Just Take It Anywhere Only Someone You Trust. Best To You The first thing that popped into my mind when I read this is the disgusting smell of differential oil, its possible you've damaged the rear diff. answer sounds to me like u hit the catalictic converter and damaged it the damage doesnt mean u have a hole in it, but a dent can mess up the insides of catalictic converter get under car and look to see if this is banged up.