Hi bshah,
It is quite possible that the pain in the middle portion of skull is due to TMJ. TMJ occurs in people who have a habit of chewing gum or who tend to clench their teeth.
Other possibility in your case can be high BP. Is your BP adequately controlled?
It is important to rule out intracranial causes of pain like brain tumor or aneurysm although your CT results have been negative. So please go ahead and get it done.
I too have developed a similar pain on my middle upper portion of my skull fro left to right.i had a cat scan w/o contrast done was negative.i am planning to go for MRI tomorrow.the pain is scarry as i have a blood pressure problem.
bina/newjersey.