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 dizziness or nystagmus occurs with possible stroke or another acute neurological problem, including:
New facial drooping, arm or leg weakness, or numbness
New trouble speaking, understanding speech, or swallowing
Sudden severe difficulty standing or walking
New double vision, loss of vision, or marked loss of coordination
A sudden severe headache unlike your usual headaches
Collapse, loss of consciousness, or a seizure
Do not drive yourself for emergency assessment.
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 prompt medical advice if you have new hearing loss, severe ear symptoms, repeated vomiting, recent head injury, or dizziness that remains continuous rather than occurring only with position changes.
Sudden hearing loss should be assessed urgently because early treatment may matter.
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment if you develop repeated brief spinning episodes when rolling over, lying back, looking up, or bending down.
Assessment is also appropriate if symptoms interfere with walking, work, sleep, or driving.
Every sign above is quoted from the sofidex article on Paroxysmal positional nystagmus. If you are not sure, err upward — it is always reasonable to be checked.