Since every headache is different and don't dismiss it as not being a migraine, there are many different types. Some make you sensitive to movement, some to bright lights and movement, some are localized and some are general.
Factors that could cause a headache that you described:
1) Change in diet
2) Too much caffiene, not enough caffiene
3) MSG in your food (I get had headaches if I eat too many foods with it)
4) Low Blood Sugar/High blood sugar
5) Change in weather patterns (high pressure/low pressure)
6) Allergies
7) Reading too much, need glasses or your current prescription is out of date
8) Too much computer/tv
9) Improper lighting/Bright sun cheap sunglasses