Your wife has got chronic cough which is defined as cough lasting for more than 8 weeks. Important differential diagnosis includes cough variant asthma
, eosinophilic bronchitis
, ACE inhibitor
group of anti hypertensives, gastroesophageal reflux, upper airway cough syndrome etc
you must go for early morning sputum for acid fast bacilli, sputum for eosinophilia, chest xray
if your doctor is suspecting narrowing of eind pipe medically termed as bronchoconstriction
, you must go for a simple breathing test called spirometry with reversibility testing....
If it comes out to be positive then inhaled bronchodilators will be of great help...