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It is difficult to comment without examination. In your case it could be a lymph node. You may not have been sick but local infections like dandruff or dermatitis too can cause a lymph node to swell and be tender. It could also be a folliculitis (hair follicle infection) or an abscess. An infected cyst is also a possibility.
It is difficult to comment beyond this at this stage. Do consult a doctor and get this examined. Please let me know if there is any thing else and do keep me posted. Take care!
Thanks for the reply. I have an appointment booked for Monday evening so hopefully that should shed some more light on it.
The lump has burst again over night and has gone down a bit, but it is still quite tender and sore looking. I think my main fear was that it may be related to some form of Cancer, being in that particular position behind my ear.
Thank you again for your reply, and I will indeed keep you informed of my progress.
In all probability it is not cancer at all! Rest assured!