2002 Subaru Forester Rear Brakes????????

I hace the original rear barkes on my car (I do not ride the brake pedal). For over a month now when ever I step on the brake pedal I have this noise . Sounds like it is coming from the right rear brake area. It sounds like squeaky bed springs!!!!!! It isn't terribly loud but it driving me nuts.I had my rear brakes checked twice by the same garage guy that does my front brakes etc. He says my rear brakes are fine. I live in Western New York State where we get 4 seasons (lake ettect snow in winter)I hear this sound braking going forward and backward. I keep thinking shocks but this only happens when I brake! I'm really confused. Help!