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 difficulty breathing, chest pain, fainting, confusion, or bleeding that is heavy or does not stop with firm pressure.
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
Contact your surgical team promptly for increasing redness, warmth, swelling, or pain; pus or bad-smelling drainage; fever; wound edges that open; a tense or uncomfortable fluid collection; or a rapidly enlarging breast.
3
Does any of this apply?
Book an appointment
These are not routine recovery symptoms.
Mention symptoms that are not improving at follow-up, even if they are not urgent.
And for anyone, someone who:
has noticed a lump, a mole that has changed, or unexplained weight loss
The article also says
Mild bruising, tenderness, and slight staining on the dressing can occur.
Every sign above is quoted from the sofidex article on Breast lump removal. If you are not sure, err upward — it is always reasonable to be checked.