Hello and thank you for your question. I’d be happy to assist you.
I understand your concern.
Well as you describe,his ear infection can occur from diving.
The ear tubes present behind the nose gets blocked sometime and result in negative middle ear pressure & ear blockade and this is what is happening in his case.
You should try some self care measures
Give him Children's Motrin alternately with Calpol now and just a half hour before takeoffs or landings if you know your child has ear pain when flying.
Hydrate him with plenty of fluids while air travel.
Chew gum or suck on hard candy.
You can give him OTC Xylometazoline nasal spray 0.05 %, 2 puffs Thrice daily.
Steam inhalation with menthol twice daily.
Also he should not sleep during travel.
Warm compresses on swollen gland can be helpful.
If possible see a doctor at nearby emergency room before air journey.
Let me know if you have any further query so we can discuss it thoroughly in every aspect.
It’s my pleasure to continue this conversation until you satisfy.
May I help you further?
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Waiting for your response.