When you mention pain going to your ear, the other thing that comes to mind is that there are lymph nodes behind your ear, and lymph nodes get tender and swollen in
the area of an infection.
You don't say where exactly the lump
is...is it anywhere behind your ear? Then IT could be a lymph node. It sounds like its an infection, either way, because of the way it responded to the antibiotics....most likely a sebaceous cyst.