Have them (your doctors) check you for Lyme disease. The same thing with the headaches happened to me, and no-one and nothing could offer me a reason or relief. Finally, I too was sent to a neurologist who sent me for countless tests, but he also did a full blood work up. That's when they found my Lyme titre was extremely elevated. Within 2 hours of him receiving the results, I was in the hospital having a spinal tap done to measure the pressure in my spinal fluid. Within 12 hours of that test, I was admitted to the hospital with Lyme Menigitis. Turns out, the Lyme, untreated for a severly long time, manifested itself in my spinal fluid, which in turn, caused swelling of the fluid, which caused the increasingly severe headaches. (When I was finally diagnosed, I had had a blinding, seven time middle of the night emergency room visit because I sincerely thought my head was going to explode headache for 3 months that had started months earlier as an occasional migraine.)
When I was admitted to the hospital, I was immediately placed on high dose IV antibiotics and within 24 hours, my headache was reduced to a mild pain. I was on and off the medication for almost a year total, and whenever I would stop the antibiotics and they would work their way out of my system, the headache would start back.
I also experienced chronic fatigue to the point I literally could not get out of bed or take care of myself. My husband was calling us both in sick to work so that he could help me with everything, I couldn't even shower by myself because I was too weak to stand for long periods of time. Everyone attributed this to stress and dealing with my two children and all their activities while working outside the home full time. This also improved as my treatment progressed.
I sincerely hope that this isn't the case for you, but it never hurts to check. Lyme disease is extremely serious and even more extremely under-diagnosed in the state of Maryland.
HTH,
Kymber