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 for severe breathing difficulty, chest pain, coughing up blood, fainting, a seizure, or sudden severe confusion.
This is an emergency caused by dangerously low cortisol and requires immediate treatment.
If you have diagnosed ectopic Cushing syndrome, contact your care team promptly for fever, infection symptoms, worsening swelling, new medication side effects, or the clear return of previous cortisol-related symptoms.
Seek urgent medical assessment for:
Arrange medical follow-up for gradual changes such as increasing weakness, unexplained bruising, worsening blood pressure or blood sugar, new stretch marks, menstrual changes, or persistent mood symptoms.
These symptoms have many possible causes and need proper assessment.
The article also says
After cortisol-lowering treatment or adrenal surgery, severe weakness, vomiting, abdominal pain, fainting, or confusion may indicate an adrenal crisis.
Every sign above is quoted from the sofidex article on Ectopic Cushing syndrome. If you are not sure, err upward — it is always reasonable to be checked.