M.B.
R.,
Do you have an aging carpet in your bedroom?
DS would sneeze up a storm when we had him in the bedroom. We have baseboard heating, dry, yes, but we couldn't help anything until we removed the carpet from our room - it was dated 1989 underneath!
Carpets, depending on how they are manufactured, can last 5-12 years. Ours was 19 years old! Ick!
Removal not possible? Use a steam cleaner - when baby is not home. Clean it until the water comes out clean - not cloudy or black.
If you can't clean the entire carpet in less than 24 hours (however many times it takes to get the water clean) then it is time to remove it!
Good luck,
M.