14 days ago tomorrow on Sept 21, 2015, I hit top of my head hard enough to knock me down. No cut as had on a cap but head hurting badly and puffing some on crown. Went to ER where a CT Scan was done. Doctor said brain was fine, no sign of blood ( my main worry), said good thing had on cap and have a hard head. However, still having headaches periodically but another is at times there is a "stinging sensation on top of my head, like ants moving around and makes me want to scratch my head vigorously. What can be causing this? Went to my primary care doctor Oct 1st and he did not seem worried as he had report from the ER doctor but this stinging, burning, itchy sensation is really bothering me. What can it be?