I have a funky smell coming from a few registers. It's a stinky smell--like piss or barf or maybe a tad mildewy but my wife says it doesn't smell like mildew to her. Nonetheless, it's stinky. The strongest is in our upstairs master bath which is 12-15 feet west of the FAU. The next area of smell is my daughter's room which is also 12-15 feet away south and upstairs as well. A couple other upstairs rooms get it but not as bad. I don't think we smell it anywhere downstairs. The smell weakens and goes away after 15-30 minutes. It's only at start up, too. Been going on a couple months. I changed the filter but that didn't help. Is there water pooling somewhere? Or is there a dead animal in or near a duct? Your thoughts? Thanks!