Headache pressure and pain

On day, I had a strong dizzy spell followed by what I thought was a typical migraine.  Now, for the past 6 weeks, I have had severe headaches that mimic migraines, but with pressure building in the left temple, the center back of my head and forehead.  It feels as if cement has been packed into the left temple and I am wearing a cement helmet on top of my head all day, every day.  If I lay flat on the back of my head, the pressure immediately builds around my left temple.  CT scan, MRI and MRA all negative.  Awaiting CT of sinuses.  Prednisone, Z-pack, Midrin, Ibuprofen nor Butalbital have helped.