There's a squeeking coming from my car when i'm braking.

i thought it was the front pads, those are fine, they are nice and thick still, i check the rear pads, the driver side rear rotor seems to be warped, when i spin the wheel, i hear a scratching sound. this is not suppose to happen correct? it doesn't free spin, it will scratch and stop.

should i replace the pad first and then the rotor or replace both and see if they are the problem ( i already have the brake pads )

 

i had a small pebble or something get stuck and it scratched my right rear rotor so while driving i would hear a metallic whooshing sound...i just replaced my rear rotors and pads