Scalp Pain-Inflammed

I have had a pain under my scalp that seems to go from one side to the other. Right at the top of my head.  The only way I can describe it is as if someone beat me over the head in one spot or got my hair pulled super hard. It hurts to the touch, even hurts to lay on my pillow if I lay in that area. I seem to have had some visual issues as well, not sure if it's hand in hand.  

I am uninsured & I know an MRI would be really expensive. I'm afraid as I'm a cancer survivor & so worried it's something serious that I can't find out how to treat without a Dr or diagnosis.