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 breathing difficulty, fainting, a first seizure, a seizure lasting several minutes, or difficulty waking.
Follow the treatment team’s emergency instructions and contact the cancer service immediately rather than waiting for a routine appointment.
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 urgent medical help for:
New facial, neck, or arm swelling with chest symptoms
A severe or rapidly worsening headache with vomiting
New double vision, weakness, confusion, or marked drowsiness
Difficulty passing urine or sudden loss of bowel or bladder control
3
Does any of this apply?
Book an appointment
Arrange a medical appointment for a persistent lump, unexplained chest or abdominal pressure, recurring headaches, ongoing vomiting, unusual thirst and urination, or symptoms that continue to worsen.
The article also says
During chemotherapy, fever can indicate a serious infection when white blood cell levels are low.
Every sign above is quoted from the sofidex article on Extragonadal germ cell tumors. If you are not sure, err upward — it is always reasonable to be checked.