I Have An Intermittent Pin Prick Pain In The Left

I have an intermittent pin prick pain in the left side of my head back from my temple and above my ear towards the front of my head. It feels like a single hair is being pulled out of my scalp. A few weeks ago I hit my head on the lid of a trunk of a hatchback in this spot. My vision is ok not blurry but not as good as it was, I am due for an eye exam. I don't have a headache just an intermittent dull ache but it doesn't last very long.