I am sorry that you are having such bad headaches! Although headaches are of course really common, when they become persistent and severe, doctors
do start to worry about a potentially serious cause of the headaches. These serious causes include a tumor in the brain, which is the first thing that usually needs to be ruled out. It sounds like this is the reason that your doctor did an MRI which, if it is negative, is very good news because an MRI is very effective at detecting tumors in the brain.
The question of the pituitary gland is also related to the potential of a tumor or cyst. The pituitary gland is a small gland that sits under the brain and is a frequent site of small tumors or cysts which can press on the brain and cause headache. Often, the MRI of the brain also captures pictures of the pituitary gland, which can be helpful for ruling out a tumor there. However, sometimes the images are not perfect for looking at the pituitary gland and another study might be needed.
I would suggest that you sit down again with the doctor, either the primary care doctor
or the neurologist
, who is working up your headaches and ask them specifically if this is what they are thinking of and, if so, what the next steps should be.