What Is The Remedy For Cough With Allergy When On Cortisone?

I've been coughing on and off for the last 10 years. I have a bad sinus/allergie problem, and was tested for everything possible. I've got the normal allergies that seems normal to me, doghair, grass, dust…… but my sinus problem gives me a awfull sinusdrip and then I start coughing. It prolongs for sometimes up to 3months and then just stops and I'm over it. Over the years I have been to so many doctors and tried so many "new" medicine but I have learned that nothing really helps. They put me on all kind of Cortisone, Cough Meds, Antibiotics, Asma Inhalers, Bronch Inhalers, Nose drops/pumbs…but to no real help. I have been tested for TB about 5 years again that for Negative. Like now I've been coughing for 3 weeks, and have a constant headacne and are tired all the time. I hate it, because I've got no energy and dont want to feel like this. I'm 48 years of age, healthy female, excersise 3 times a week, dont smoke, take a whisky every evening…quite normal I think.
My housedoctor has me on Monte-Air 10mg one at bedtime at the moment, and also cortisone for 8 days, I've got 2 tablets of the cortisone left and also Solpylex cough medicine. Have you maybe got any any suggestions for me?