5 months boy having pneumonia. Suggest,

Hello Sir, My son when 3 months old, was having cough from past 1 month which continous for almost 10 - 15 secs. Had blood and throat swab tests done but they were negetive. X-ray showed mucus in the lungs and during first hospitalization he under went bronchoscopy later discharged and with in 10 days his cough reappeared and x-ray showed mucus in the lungs. 2nd time hospitalization was done and he was given anti biotics - cefuroxime and clarithromycin which controlled his coughing periods, however not upto 0 level. Neither it was pertusis cough. Mucus was also cleared through antibiotics. He was discharged on 3rd feb and i see his coughing has reduced. He was on oral dosage of cefuroxime and clarithromycin antibiotics post discharge. Now he is 5 months old and we planned a 2 days travel & cough reappeared. Gave Azithromycin for 5 days, cough reduced but in early morning it is a bit. Plz suggest, Thank you !!