Could it be a combination of things? I know how
frustrated you must be. You want to get down
to the bottom of this, you want to feel well...and yet, they are not finding anything.
If I were you, I would probably turn to a multi-vit w/mineral, look into the menopause...would HRT bring you any relief?
From what I understand, a reduction in a hormone (I think Estrogen, in this case) can bring on sinus issues & dryness (in all the "wrong" places).