Welcome to HCM,
After going through your history it looks that you have chest infection
which is most likely bacterial as you are a chronic smoker there is strong possibility of chronic Bronchitis
and acute exacerbation caused by infection.
If there is narrowing of airways along with blocking of airways it causes not only cough but also shortness of breath
You are required to be examined by a chest Physician or a Internal medicine to decide about relevant investigations like complete blood count
,an X ray chest,Pulmonary function test,sputum staining and culture to identify micro organisms.
Depending on result appropriate therapy would help you lot but you need to quit smoking.
Antibiotics, bronchodilators,Cough expectorants,mucolytic and Oxygen therapy
if required will used and you will improve hopefully please take care and once again please quit smoking.