question: I have a hard lump on the back of my neck at the base of my skull.  I have had this lump for a couple of weeks now.  It is hard and immovable and it shrinks and grows throughout the day.  A couple of different times, it has hurt.  This pain usually occurs in the morning and then goes away.  It is bigger when it is painful and then it shrinks back down again.  I had a stiff neck for about 2 weeks before the lump appeared. What could this be?