Headaches, lump on side of head, blackout

I am 20 years old and recently found a lump on the side of my head. I didn't go in right away because it didn't really worry me. Then I started getting really bad headaches, sometimes one everyday. The weird thing is that I get these headaches most often on or near the lump. Then sometimes when I am walking or standing I get overcome with dizziness and I black out. Any ideas what could cause this?