Infection cold season. Solution!

Almost from 3 year.. Suddenly I start coughing in winter season cough syrup don't work ..my coughing can last upto 5-10 minutes..my chest xray shows infection on chest.Diffrent doctor said diffrent things some said it due to allergy which I develop in winter I get cough and chest infection in xray which some doctor said bronchitis.they give me medicine for 1-2 month for this.I lose weight that time.Some doctor said It will keep happening.some said find solutions in homeopathy or ayurvedics.Some said excersize which reduce allergy and it's not a big deal. Every year I suffer for 2 month and lots of money and time wasted for this.I continuously cough for 10 minute without phlems just water thin mucus comes out.I feel more pain and suffering then typhoid.I visited 2 times ent specialist one time localdoctor diff year.They can't even say in confidence that I have allergy or not .they are not sure.I was the first one to hint them I maybe have cold allergy.please advice howtofind solution!!!