Also if its not a stone or something .......
FIRST ........ lift wheel off ground and Give wheel a shake in all direction in case its a wheel bearing ...... do not shake the wheel without the car being well supported .... do not rely on car jack as a car landing on your arms often offends....use an axle stand ....... also .... if its grinding on turning or sometimes going straight it could be a cv joint grinding ... had this symptom as well ...... but if pads are wearing fast my best guess is a sticky calliper piston ......
Check all calliper bolts etc are tight... as you said pads have been replaced recently it could be something not done up right .....
Other thing to check is that all the Calliper sliders etc are clean and moving freely as if they are stuck or sticking they will cause rubbing........... if a calliper piston is sticking a bit it can cause this also , you can clean up the piston by pumping it out a little and cleaning with a toothbrush and autosolve ...... BUT ........DO NOT pump out the piston a little to clean it unless you have a definate method of pushing the piston back in because they can be a biatch ! Do not put too much stress on the brake hoses when you do this.
I use a G clamp... dont damage the piston face ..I have a clamp that fits inside the piston but you could use wood to protect piston face.... and always ensure you can push in a little BEFORE YOU pump out piston a little ... cos if it cant be pushed back in ie its partly seized which may be the whole problem ...... your stuffed !... dont push out too far cos if it pops out you will have to refit the piston and bleed ..take a look on ebay at calliper pistons to give you an idea of how long they are ....... unless your up for removing the piston or the piston is not cleaning up/freeing itself ... and thats your only option.
Dirty pistons can get stuck and not retract a little which is what they are meant to do .. causing binding ... you will usually feel this if you try to spin the wheel while lifted off the ground. A little scraping sound in normal but if there is a lot of resistance its likely the piston that needs cleaning/replacing....... or the wheel bearings fubared...... If your not sure which remove the calliper and see if the wheel is still hard to spin .. if it is .. its your bearing thats gone..... just replaced a mondeo rear wheel bearing where you literally can only turn it with a crowbar although its was only making a light grumbling sound when driving.
Check piston dust seals .. any leaks or signs of brake fluid loss at calliper or level dropping at master cylinder...... ?
I use the bikers method to clean a piston ..... either pump out a little .... clean with autosolve on toothbrush ... wipe off ... push piston in .... pump back out .. remove more gunge .... clean .... push in ..... and do this until no more gunge .... DO not use anything other than autosolve or brake cleaner to remove dirt .... if there are pits and holes / scratches .. replace piston or calliper ... when pumping out dont put foot to floor on brake pedal ... push a little to guage how far out the piston has moved .... otherwise you could shoot the piston out of the calliper lol
Do not grab pistons with pliers etc ever .... any damage to piston sides means they are scrap
OR remove piston and clean on flat surface with cloth on it ... rubbing piston in autosolve until lovely and shiny .... replace new seal and dust seal ..... bleed brakes and jobs a good un...... as long as you are confident in doing this .... has to all be perfectly clean if you remove ... clean calliper, clean bench.......
When refitting the pads ... little smear of copper ease on back of pads that touch pistons and also where the calliper "fingers" touch the other brake pad .... stops squealing.... .... not too much as you dont want that on the pad faces.
You can use a light smear of red rubber grease on the sliders .... light ... not smothered !
Metal to metal feeling can also happen after dics have got damp overnight and formed a film of rust on them ... which you then feel when you brake the first few times .. this is normal.
Sorry trying to cover all the bases ......
Does the car brake in a straight line or pull to one side ?
Sorry if this comes over as treating you like you know nothing .... dont know your experience level ..... and finally .. do not touch this if your not confident mechanically .... brakes are way too important to mess with..... take the car to garage .. a good mechanic will suss out problem in minutes ... and then its your choice if you pay them to fix or DIY
