Hi
Welcome to the MedHelp forum!
It is difficult to comment without examination. Lump behind the ear could be an abscess, folliculitis (hair follicle infection), lipoma (localized collection of fat), a cyst, an inflamed lymph node or a neurofibroma (localized harmless swelling in of nerve and connective tissue).
You may not have been sick but local infections like dandruff or dermatitis too can cause a lymph node. Watch the lump. Do not touch everyday but once in 10-15 days. If the lump increases in size, becomes painful, changes color, bleeds, changes shape or consistency or more similar lumps appear then consult a doctor (it would be good if you can go to a walk in clinic and get this examined). Hope this helps. Take care!
Go to the doctor, have it tested.
if it doesnt pain, it seems it is just excess skin or tissue growth. It does not need attention unless it hurts...Dont worry!
Parth Adhyaru