My suggestion is to have your doctor take a look at it. It could be a swollen lymph node, which means you probably have an infection or inflammation somewhere in the area, or it could be something else that could require a doctor's attention. Better safe than sorry.
Sounds like you may have an abscess, seek treatment from a Dr so he/she can determine whether it needs to be drained.
Does this lump cause any pain upon touching it?
It could be something as simple as a blocked pore behind your ear, that just needs to be emptied somehow. I get them occasionally, and they can tend to be a royal pain in the neck, until it is gone, but it would be a good idea to have it looked at, before trying to do anything with it yet.