I am not a doctor, but just read your post and suggest you read about LPR-silent reflux, you can google it.
I suffer from it and it sounds VERY much like that could be what your wife has. It's acid reflux and she discribed many of the classic symptoms.
A good ENT or gastroenterologist will diagnose for sure.
p.s. you can jump to the acid reflux boards and get info there as well...