I have a chronic cough for y ars now with excessive mucus from throat, the cough is bad at night and early morning when u wake up, also in closed spaces, having a reflux problem I take Nexium 40mgdaily for years now, nothing helps this cough, I did all tests, no allergy, clean lungs. I feel exhausted from this cough that is really downgrading my life style...what needs to be done?