Hiya-
Sorry that your getting these headaches. Unfortunately headaches are very common. More common that brain tumors. Also headaches can be a pain. Seriously if you are in pain you should ask to be referred to pain management (PM). They will look to treat your pain but the good ones also try to figure out why you are having it.
There is a great forum for headaches sufferers here on Medhelp.
http://www.medhelp.org/forums/Migraines--Headaches/
If after you read the posts in the other forum and you are still worried that you might have a brain tumor, tell your doctor. (Well you should do that anyway) With pituitary tumors they test your hormones first. So to ease your mind that your doctor could run testing for your thyroid, prolactin, and sex hormones. If these show irregularities then it could justify ordering an MRI.
I suffer from a constant headache. I used to have a pituitary tumor. My headache began after my surgery to remove it. So my treatment is very much like what another headache sufferer would get. It's just that they know exactly what nerve and what area is damaged and causing the pain.
Horselip
If the docs hear your lifestyle and your stress levels, it is pretty understandable that you would have a tension headache and if you look that up, it is pretty much described how you say it. As well, if you had a tumor that caused headaches, nothing is going to make it go away after a while to my thinking save taking away the mass effect issue - as in removing the tumor. The neuro is also looking for other symptoms in your reflexes, gait and other signs - you must not have those.
You can go see an eye doc who can check your eyes and optic nerves too for a further check but if you look here - I think most posts are "I have a headache I think I have a brain tumor"...