Coughing and trying to gag

I have a 16mth old that was diagnosed with laryngomalacia at 1mth old. He now doesn't have  his trach tube anymore, but the reason y i am writing this is because when he coughs he sounds like he is trying to gag but he doesn't. What causes that?

[National Jewish Health]

The sound of "trying to gag" may be related to the cause of his cough, be it gastroesophageal reflux disease (GERD), postnasal drip or the accumulation of mucus in and around his larynx due to impaired mucus clearance.  Any of these could be associated with recurrent aspiration.  You should discuss this with his doctor, most expert in the management of laryngomalacia, with reference to the appropriateness of further testing of his airways and his swallowing mechanism.