I looked at your picture link. Is it the lump area on the left side of your forehead (when looking at you)? You didn't hit yourself there? Does it hurt? I think since it has been 6 months, you need to get it checked out. Do you have any sinus issues?
Hello~I agree with the above poster, since this has been an on-going issue for 6 months, it would be wise to have it checked by your GP.