I been geting real sharp pains in the back of my head for the past 2 or 3 years, and it only happens when i throw a ball like a football. But it dosent happen very often it has been geting worst each time. The location is is always on the back left side mf my head, then after about the pain goes away, there numbness for a few minutes. I was hope that you can tell me what it might be and let me know how bad it may be.