A small hard lump on the back of your head is not normal for you if it was not there before. You may have hit your head, or it may be an inflamed lymph node. Seek the help of a qualified physician...
Could be anything from lymphoma(uncurable lymph node tumor),a harmless cyst or a lethal skin tumor on the scalp.Try searhing for websites that show tumor symptoms.God bless you.
Probably a Lipoma.
If the lump moves easily, it is most likely a benign fatty-tissue structure called a lipoma. These are common in the lumbar region myofascial tissues, and often are not treated.
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