When I was younger, from about 9-22 years of age, I had severe headaches. I don't know what caused them and never really researched them. Sometimes I couldn't get up because the pain was so intense, other times I would easily get irate at people because of the pain.
One day I woke up and knew something was different but wasn't sure exactly what, kind of similar to noticing something is different about your friend and you haven't realized what it is yet. And then it comes to you, oh no more braces, or a haircut, well just like that I noticed my headache was gone.
To this day ( and I actually have one right now) I still have headaches and even the ones that leave me curled up in my bed moaning while tears are streaming down the side of my face. They hurt!
I don't have a suggestion for your prolonged issue other than a CT scan or MRI or whatever does a brain scan, because it is possible you have a tumor or pressure in your skull( I watch way too much HOUSE).
But something that TOTALLY works for me with my temporary headaches is Excedrin. On a scale of 1-10, 1=weakest 10=extremely painful, I take two of the maximum strength for a 1-6 headache and three for a 6-10 headache. IF you notice the overlap on 6, its because when it gets to that level sometimes you can't be sure whether or not it will get worse, so i am cautious.
I am not a doctor, nor claim that my situation can resolve another persons medical condition. This did, and continues to help me when I have the issue as described above. With ANY advice, always make sure to get a second opinion from your doctor or nurse hotline.
I hope this helps!!