I cough for a month every 9-12 months?

Im suffering from chronic coughs every 9-12 months. for example last august I got a cold/flu and soon after I started coughing for a month. nothing helped cough syrups symbicort....nothing. just last month I started suffering from season allergies. symptoms were runny nose, itchy throat and ears and red eyes. however these symptoms stopped suddenly last week and it just turned it to severe dry coughs. it's funny, some days I cough less than others. but again nothing helps relieve symptoms. i have also tried allergy pills. I also have this tickling sensation in my throat which I think triggers the cough. doctors just prescribe cough medicine to no effect. what am I suffering from? why do I get this every year?