what is causing the grinding in the left rear brakes?

What is your question?

It started grinding one day without prior squeaking or warning... It's only the driver side rear brakes making the noise. The brake pads appear to be ok still. When I went to inspect it, I had a hard time removing the rim off the car after I had all the lugs off. I literally had to use a pry bar to get it to break free from the vehicle. Have never heard of that before. usually the tire is ready to fall off when lugs are removed. Is this related to the brake issue and what could be the cause?

How long has your 2002 Mazda Protege5 had this problem?

few days, like 3 days