This exact same thing happened to a friend of mine 4 weeks ago. Look around the house and see if you have those Glade fragrance things, candles with fragrance, for her it was the laundry product she was using. She totally stopped using "commercial, over the counter cleaners" Stopped using bleach.... basically changed their home environment and in less than 24 hours Bryson was normal.
If you are curious and want to know what she switched to, let me know. This may not be your situation at all, let me know if you want to know more.