I have a Moen L82839 tub and shower faucet. When the water is coming out of the tub faucet it is fine but when it comes out of the shower it makes a LOUD squeal. Our house is about 5 years old and this started about 6 months ago? It is in the guest bathroom so I don't know for sure when but sometime within the last 6 to 8 months. Anyone have any ideas of how what could cause this?

Thanks,

Ken