constant griding or just noise when brakes are applied?
if its noisy when brakes are applied its prolly the indicators on your brake pads...ie they're low. When u do the change you can take them out if it shits you...even when they do start to make noise theres normally a reasonable amount of pad left anyway so you could prolly get another 5k on them
if its constant griding you've prolly already worn your pads out and are chewing into your rotors. Dont let this happen for too long as you'll have to replace shit...as it is you may get away with having the rotors machined
to find out stick your finger in the caliper bracket to see if theres any pad left