I had driver wheel bearing replaced. And was told other side was good. Now I keep hearing a noise that sounds like a bad bearing. But my mechanic rotated the tires. What is it? It gets louder as I'm going downhill

And the 'mechanic' that actually worked on the car says???..... Was it driven after the driver wheel bearing was replaced , to confirm the original noise/problem was fixed correctly? Did they change the wrong bearing or could it have possibly been both bearings were bad? bring it back to where the work was done for another test drive WITH them .