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 severe difficulty breathing, blue or grey lips, fainting, new confusion, coughing up more than a small streak of blood, or chest pain after a major crash or fall.
These symptoms can indicate damage to a lung or another internal organ.
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
Arrange a prompt medical assessment after a significant chest injury, especially if pain is making it difficult to breathe deeply.
Earlier assessment is also sensible if you take blood-thinning medicine, have osteoporosis, or developed rib pain without a clear injury.
Seek urgent medical advice if you develop:
Increasing breathlessness rather than gradual improvement
Fever, a worsening cough, or yellow or green mucus
Pain that is getting worse or is not controlled enough to breathe deeply
New abdominal or shoulder pain
Continuing pain or clicking after several weeks
And for anyone, someone who:
has a wound that is hot, spreading red, or leaking pus
Every sign above is quoted from the sofidex article on Fractured rib. If you are not sure, err upward — it is always reasonable to be checked.