Glad you got the all clear from your doc
I will add a few more things for those people who are reading this thread and perhaps get headaches themselves;
I will also add that you can get headaches if your body goes in to ketosis - basically if it starts using protein for energy rather than carbs - got a few shocking ones when i tried out aitkins (low/no card diet).
Also when my body goes through changes in diet etc I tend to get headahces. Ie new diet, quitting smoking, not drinking coffee etc. I'm not sure why I get them during these periods, however they usually go after a few days as my body adjusts and I dont worry about them.
However when i start getting a headache my first thought is, 'how much water have I drunk' as that was almost always the culprit - second is tension headaches from heat, sun, or stress environments like shopping or soemthing. I am quite concerned with my headaches, as occaionally they escalate to migraines (usually in intense stress or heat).