Keep an everything journal, lol
For sure keep a food journal, and I would also just jot down everything you do for the day. I know it sounds like much, but triggers can be so many different things and the best treatment (IMO) is avoiding as much as you can. I've been doing that so my doctor and I can work out the (second) best treatments.
For example, mine are cleaning products, which I never bothered to narrow down, I just got rid of everything.
Scented candles/room sprays
I think also big cities get to me, the pollution, the noise, all that good stuff. Although I was in Paris for a few days and it wasn't too bad.
I haven't noticed anything food related. I eat mostly whole foods. (well, try to
Oh and flying long distances!!! I hate that one, I can't avoid it.
Other people have reported random things like onions (which is apparently somewhat common, who knew). Some people say MSG. Some people stress.
Things you can write down: What you were doing, where you are, what you were using, how the headache feels, how quickly it came about, where it's located, how long it lasts, the severity (maybe a 1-10 scale) and what you did to try to get rid of it.
If you decide to visit a doctor all that information will be helpful.