Diet is often over-looked when searching for culprits of headaches. Everyone usually utilizes some form of relaxation methods or modalities thinking the cause is because of stress. Or, go to the chiropractor thinking that they may need an adjustment. Or take an aspirin because they think they are aspirin-deficient! ;)
No one wants to change their diet ..... let's face it..... our lives are based around food (the not-so-good-for-you kind of food, for that matter). It's easier to pop that pill then it is to change the way we eat and sustain it. I was researching migraines for a project and found out that hormone imbalances play a major role in headaches. A good diet plan would help to get this in check.
The best diet that I can think of that is also the most nutritious is a raw vegan diet. Now, you don't have to be 100% raw to see major and positive changes: 70 - 85% raw will make a big difference. I know that headaches can be very debilitating and if it took eating a ton of salads, raw fruits, green or fruit smoothies, etc., for a few weeks, I would definitely give it a shot. It's helped me out tremendously with a few ailments for which I suffered!!