small penny sized lump on the back of my head, below the hairline closer to my left ear. Never noticed this till few weeks ago. Recently suffered from a mind numbing headache cause me to black out a bit and have to sit down. (though this type of headache has only happened twice). Also have headaches left unreleived with the aid of ibeprofin, had to sleep them off. (if i could get to sleep) Im 18, 106 pounds and have a minor case of pots disease. (heart problem, circulaion is bad basiclly). Im an active individual and in the middle of obtaining a biology degree. What is this lump?