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 for sudden, new loss of coordination, particularly if it occurs with:
Facial drooping, arm or leg weakness, or numbness
New trouble speaking, understanding, or seeing
A severe or unusual headache
Confusion, collapse, seizure, or loss of consciousness
Inability to stand or walk safely
Symptoms after a significant head injury
Severe drowsiness, slowed breathing, or possible overdose
These signs can occur with stroke or another time-sensitive condition.
Note when the symptoms started, and do not drive yourself for care.
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 coordination has recently worsened, you are falling repeatedly, or symptoms began after starting or changing a medicine.
A child with a new unsteady walk or unexplained loss of coordination should also receive prompt assessment.
3
Does any of this apply?
Book an appointment
Book a routine appointment if mild symptoms persist, keep returning, or gradually worsen.
Assessment is also appropriate if coordination problems interfere with work, school, driving, or everyday tasks.
Every sign above is quoted from the sofidex article on Movement - uncoordinated. If you are not sure, err upward — it is always reasonable to be checked.