My filter started making really high pitched buzzing noises like three days ago.. and it still hasn't stopped. Any ideas on what it could be or what to do about it?
It depends on what you call a filter. It could be anything from a new source of air in the system or something in the impeller (or not in the impeller).
Clean the impeller housing and inspect the impeller for excessive wear. Take the unit into the kitchen and spray it out while it is upside down over the sink (to flush out dirt and build up).