do you live in apartment or rent?  maybe previous owners of the house
treated with something and your little ones are smelling THE TOXINS from
that.  do they sleep on the paper bedding or use it for litter?  Do you
live close to a factor or a plant that make some material and the fumes
could be in the air ? === AIR Conditionar is leaking something?
 
WELL THERE IS SOME OF MY IDEAS HOPE IT WORKS OUT
[Posted in FML issue 4489]