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
Seek emergency help for chest pain that is severe, unexplained, or accompanied by:
Pressure, squeezing, or heaviness in the chest
Shortness of breath, fainting, marked weakness, or confusion
Sweating, nausea, or vomiting
Pain spreading to the arm, shoulder, jaw, neck, or back
Coughing up blood
A very fast or irregular heartbeat
Sudden chest pain with breathing difficulty
Do not rely on tenderness or a previous costochondritis diagnosis to rule out an emergency.
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
Prompt medical assessment is appropriate if you develop fever, redness, warmth, visible swelling, a new lump, or pain after a significant chest injury.
These features are not typical of uncomplicated costochondritis.
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment if chest pain is new, keeps returning, lasts longer than expected, or is affecting sleep and daily activity.
You should also seek review if pain treatment is not helping or you need it frequently.
The article also says
Heart attack symptoms are not always dramatic and can differ from person to person.
Every sign above is quoted from the sofidex article on Costochondritis. If you are not sure, err upward — it is always reasonable to be checked.