Hello.my Child Who Is 6.5 Months Old Has Congestion N

hello.my child who is 6.5 months old has congestion n when he coughs it feels that the mucus is waiting to be released...the doc said chest is clear and gave him ambrolite-s 3.5ml 2times daily n sinarest af 3.5ml 2times daily after which the cold subsided n the frequency of coughing came down..but nw after almost 5 days whenever he coughs i can feel the congestion n its difficult for him...last when he was around 4 months old he had a similar episode but then he was directly given azithromycin drops for 5 days n saline nebulisation was advised n he recovered well...so i dnt know whether this time the same has to be done n i am not willing to give him so much of syrups daily..please advise..