Mazda 323 (Protege) 1997 Rear brakes problem

1997 Mazda 323 (Protege) with 1.5 engine and rear drum brakes, no ABS.

The rear brakes were repaired a year ago with new cylinders and shoes. Now the brakes work OK, passed the inspection, but when I drive at higher speeds for a while and come to a stop, the brakes (the passenger side rear drum) make a horrible (metal-to-metal, sounds like bad bus brakes) noise. If I press the brake pedal gentlier, the noise is worse. When the brakes start to make noise, there is also a speed-dependant noise when driving at slower speeds (less than 40mp/h). If I let the car stay for over ten minutes, the problem disappears until I drive at higher speed again.

I have sanded the shoes and the drum with a fine sand paper after the problem started, but it didn't help. Also changed the right rear cylinder but nothing changed.

The shoes and the drum look ok and the cylinder has not leaked. The problem started after the car was without driving for over a month, and the parking brake was on.