Anyone ever have this? When i back out of the garage and also when I put it in D I get a clicking/popping noise from the RR brake of the truck.

Now the other night I was at my parents and had my ebrake on since their driveway is sloped. When I disengaged it, it popped loud. The next day I noticed the inside of the rim was speckled with brake dust. The ebrake pedal feels soft also when i engage it. Brake fluid is good though.

Any input?