How To Cure Chronic Cough Due To Asthma And Sinus Infection?

Hi, I am a 71 year old with controlled asthma. I had a sinus infection 6 months ago, have had every antibiotic and cough syrup imaginable. I don t drink alcohol or smoke..ever. The cough has not gone away. No one can find a cause. I am unable to do much because the cough is devastating. I m a world traveler, very productive and love God and life. This cough has taken on a life of its own and I m worn out. I take GERD meds, everything I ve been told. Pulmonary Doc just called and reviewed my chart; doesn t feel he needs to see me until he has time. Everyone says they can t find a reason..