I Have Never Smoked And Have Had A Relatively Healthy

I have never smoked and have had a relatively healthy lifestyle, no fried, fast foods, and exercise, etc. about five months ago I began coughing and coughing up an excessive amts. of phlegm to the point it would wake me up at night and in the public., strangers asked if I needed help. I was seen by an allergist, no allergies with patch test, diagnosis, non specific allergies. Put on pulmacort, symbacort and Zyrtec inhaler plus another. I also have been taking benedryl, none of this helped. Saw apulmonologist yesterday. Tested breathing, normal oxygen level, chest x-Ray of chest is clear. Also scoped my throat, no polyps. Am now on short dose of prednisone to break the cycle, citrazine and fluticazone inhaler once a day. If none help, cats can in four weeks. Tonight symptoms are coming back. Gerd is a non issue. Am trying to figure what is going on, any ideas. Know it is tough on line but have tried to give abbreviated history of this issue