Help! My daughter's 20 year old, 3 level townhome has an elephant in the pipes! The 3rd. Floor toilet currently does not work and is shut off. The lower level toilet works fine. The problem is with the main level toilet. For about one month, immediately after flushing and lasting until the tank fills up again, there is a hideous, loud, almost shreiking, groaning sound that can be heard throughout the whole house. It really does sound like a sick elephant! BTW this toilet is only about two years old and has never had any problems until now. Any advice greatly appreciated!