I too was diagnosed with a reactionary cough.  Whenever I would get a cold or sinus infection, my coughing would last for almost a year, every single time.  This started after I had sinus surgery almost six years ago.  I too went to many doctors to find the solution. Nothing seemed to work until my last doctor's visit with my Allergist/Asthma doc. I had perfect lung functions, just a dry hacking cough. My doc said that this type of cough is the most difficult to diagnose and treat. He said that it wasn't a smoking, allergy or asthma cough, but that my body "forgot" how to shut off the trigger for coughing.  He called it a reactionary cough.    The doc perscibed the drug Amitriptyline.  This drug is normally used for people who have chronic pain, or depression when used at 100mg.  He said that for some reason when you take this drug at a much lower dose (10mg) for one month, that it's been known to shut off the cough. My doc also thought that I still had a low grade infection, so he also perscribed an antibiotic(Amox-clav 875 mg) and Prednisone (20mg).  I've now been taking these for about two weeks, and I can say that my cough is almost gone.  The doc said if my cough goes away before one month, to still continue to take this drug for the entire month. I feel that this doc was brilliant, and me and my husband can finally get some sleep.