Have you had a MRI? I was diagnosed with a pituitary tumor (apoplectic), and all of my labs were normal prior to the onset of an immense headaches. I had many of the same symptoms you do- especially the dull headache and poor response to stress. My adrenals no longer function so I have to take a multitude of hormones daily. However, glandular adrenals and GABA seem to help me the most.