Hi thanks for contacting health care magic... You are having severe allergic cough...since long duration .... So needs for identifying causative allergen.... You can consult pulmonologist for physical examination and auscultation... You can do allergy test for identifying allergen like dust , certain foods , mould ,,pollen etc....Patch test is example for it.... And then causative allergen exposure avoided.... Drink more water.... Smoking not done if having habit ... Environmental pollution exposure limited... Fruits taken more.... When allergic congestion antihistaminic drug also useful ...No need for compulsory steroid use... Hope your concern solved. Take care.