Constant Coughing. Long will this last?

My father had severe cold and cough with fever a few days ago. On the suggestion of a doctor, started with Azithromycin 500 for 5 days. On the last day of Antibiotics, he coughed up fresh blood twice from phelgm. Doctor suggested Chest Xray PA view, which showed mildly prominent bronchovascular markings and horizontal fissure noted, which is suggestive of b/l Bronchitis (Not sure whether Acute or Chronic). All the symptoms have more or less resolved now. My question is that he is having a constant cough. This cough is mostly present when he starts talking sometimes dry and sometimes with phelgm (a few days ago the phelgm colour was yellow, now white). This coughing doesn't seem to stop. Is this cough normal after bronchitis? How long will this last?