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
Go to an emergency department immediately for sudden, severe testicle or scrotal pain, especially with nausea, vomiting, a high-riding testicle, or rapid swelling.
These may be signs of testicular torsion.
Treatment is time-sensitive, and the pain should not be assumed to come from an existing cyst.
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 advice if the scrotum becomes red, warm, or increasingly painful, particularly with fever, urinary symptoms, or discharge.
These features may suggest infection or another condition rather than a simple cyst.
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment for:
Any new lump in or beside a testicle
A known lump that is growing or changing
Ongoing aching, heaviness, or swelling
A lump that has not previously been examined
Concerns about fertility or whether treatment is needed
Every sign above is quoted from the sofidex article on Epididymal cyst. If you are not sure, err upward — it is always reasonable to be checked.