I Have A Lump Of About Three Inches Wide And

I have a lump of about three inches wide and an inch or so up/down on the back of my head. It's about two to three inches above where the head meets the neck and about ear level. It's in the center of my head and when I look up it feels like a fatty bulge. It does not hurt but it does itch a little, but that could be from me feeling it.