Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services if hearing symptoms occur with facial drooping, arm or leg weakness, trouble speaking, confusion, or a sudden severe headache.
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek same-day medical advice if you have sudden hearing loss in one or both ears, particularly if it developed over hours or a few days.
Sudden inner-ear hearing loss can feel like an ordinary blocked ear, but prompt assessment matters.
You should also seek urgent care for:
Severe or worsening ear pain
Severe spinning dizziness or difficulty walking
Blood or clear fluid coming from the ear
Hearing that suddenly becomes much worse
Ear symptoms after a head injury
3
Does any of this apply?
Book an appointment
Book a routine appointment if the blockage lasts for several days after the altitude change, keeps returning, or does not improve as congestion clears.
Arrange an assessment if pain, fever, discharge, or reduced hearing persists.
The article also says
Babies and young children should be assessed if they remain very distressed, seem unwell, or are not responding normally to sounds.
Every sign above is quoted from the sofidex article on Ear - blocked at high altitudes. If you are not sure, err upward — it is always reasonable to be checked.