About a month ago, the city came in and repaired a main water line. Ever since we have had this terrible whistling noise coming from our upstairs shower. It only happens with the hot water, and it continues until you are done using the hot water. Also in the downstairs bathroom, when the toilet is flushed it whistles as it is filling back up. We have cut the main water source off, and emptied the water lines, and opened all of the valves, and it is doing it. I am at a lost on what else to try. Any suggestions?