What Causes Constant Headache?

I have had a headache all week, mostly behind my ears and the base of my skull on the left side. I stared running fever 3 days ago. Also when I move my head the pain at the base of my skull is worse. Sometimes it's so bad I can't move my head for a minute or two. I also get a bit dizzy at times and I noticed earlier my vision blurred for a little bit. Dr diagnosed me with sinusitis but quite honestly it doesn't feel like sinus pressure to me.