Why YSK - most people who have the condition don't even realise that it is a condition, because it is just normal to them. Bloating and pain are just assumed as a standard part of eating, drinking and socialising, and whenever the issue is brought up, it often gets laughed off. You, your child, or another family member may have mentioned that they never burp. It is a good idea to take it seriously.
The official name for the condition is Retrograde Cricopharyngeal Dysfynction, also know as RCPD, or simply noburp syndrome. The symptoms can include:
a total inability to burp (obviously)
bloating after eating and drinking
constant gurgling or "frog/dinosaur" noises in the throat as the gas is pushing with nowhere to go
excessive farting (I fart about 10 times an hour on a normal day, way more if I've eaten certain foods, or drank anything carbonated)
emetophobia - fear of vomiting, because the process is very painful when the cricopharyngeal muscle can't relax.
The condition can make socialising very difficult and cause anxiety, as it is generally not approved of to be farting every few minutes, and so the bloating has nowhere to go and becomes extremely painful.
The cure! - in many countries, ENT doctors are learning about the condition, though it is slow. The condition can be permanently cured in almost 90% of cases with a single injection of Botox into the affected muscle. This effectively "resets" the nerves and their action on the muscle and allows the burp reflex to begin functioning, usually permanently. Sometimes a second or third treatment is necessary.
More info - https://en.wikipedia.org/wiki/Retrograde_cricopharyngeus_dysfunction