My shower makes an incredibly annoying and loud whining noise WHEN AND ONLY WHEN the shower is running. The noise ONLY happens when the water is directed up through the shower head. I cannot tell if the noise is coming from behind the faucet or the pipes in the wall. The whining sometimes stops for a brief second but then comes back on until the shower is turned off at which point the noise ceases. Sometimes I can alter the pitch or stop the whining by adjusting the water temperature. Help!