welcome to health care magic..
i will ask you one thing does it is painfull from past 7 yrs or pain started recently...
most common swelling is the lipoma
which is freely mobile,soft and painless..so i think it is not the problem for you..
i think it is an infected sebaceous cyst
..when you carefully observe it under torch light(ohh sorry it is on your head)you may see the dark dot on the center of the swelling..
consult general surgeon
and he will remove it by simple incision and antibiotics..
hope you will understand my suggestion..