I feel for you. Ive been down that road a few times. I dont think any advice anyone on here can give you will ease your mind, thats the horror of anxiety. If the scan is available to you,get it done, it will get rid of all doubt. Whatever you do,dont make the mistake and google it. Brain tumors are all different.Depending on where they are situated, and they have a whole host of symptoms. Some of which you will be convinced you have.
What you describe,sounds to me like tension headaches. I too suffer from them. How is your posture? You may think its good, but try straightening up and tuck in your chin,see if you get and relief.
I also suffer from occipital neuralgia,which feels like a pressure or stabbing pain in you neck and the base of your skull that travels up the side, behind the ear. Its usually characterized by a constant dull pain with short stabbing sensations and usually affects one side of the head. Sometimes it can wrap all the way around behind your eyes and into the top of your head. Ive also experienced it on both sides on a few occasions.