Big Bump On The Head, Burst, Pus Discharged, White Mark. Treatment?

i had a big lump on my head a few weeks ago it felt as if i ve been bittern by somthing and way cut the story short felt like a load of pust it burst the other week but it should have all go by now but they is still a little lump there now, just had a look at a photo of me taken on sat if you look on my head where the lump is there is a white mark looks as if a bit of my hair as come of and you can see it