Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services now for severe or rapidly worsening chest pain, serious trouble breathing, fainting, blue or grey lips, new confusion, or coughing up a large amount of blood.
You also need immediate assessment for chest pain or breathlessness with fever, especially after chest surgery, forceful vomiting, a chest injury, or a procedure involving the esophagus.
After chest surgery, contact the surgical team urgently for increasing wound drainage, spreading redness, wound separation, or new movement or clicking in the breastbone.
Do not wait for a routine appointment if these changes occur with fever, weakness, or breathing difficulty.
For known fibrosing mediastinitis, seek urgent care for new face or neck swelling, rapidly worsening breathlessness, fainting, or coughing up blood.
Routine follow-up is appropriate for stable symptoms, recovery checks, wound monitoring, and discussion of ongoing cough, reduced stamina, or swallowing difficulty that is not suddenly worsening.
Every sign above is quoted from the sofidex article on Mediastinitis. If you are not sure, err upward — it is always reasonable to be checked.