Taking long breath in between. Before.

My son suddenly started started to take deep breath on 9/5 evening, no otherissue, no fever, no cough ,no khansi, doing all activities as before, on 10th we visited a child specialist & he prescribed the medicine as per given details for 5 days. After 5 days interval of taking long breath increased, again we visited doctor added same medicine for 3 more days, he improved but still some time taking deep breath (saans kheech ke lena) . Again I visited Dr check & said he have no issue chest is looking clear, o2 level fine, it's looks like he get a habit & it will go by time. As of today 31 almost 22 days past he is taking breath in same way, I am worried it may not due to some other issue, One phenomenon seen that in case of climate change to cold, bathing for long in cold water increased the problem. No other issue playing, eating, doing all activities as before.