I've always known that if I don't eat I get headachy, but it's usually gone within 30 minutes of eating a meal. It was the 48-hour migraine with accompanying nausea that made the correlation for me -- I hadn't eaten anything for several hours because I was feeling sick, and I forced myself to eat a bit, felt a little better, got worse, ate again... after a couple of rounds of that, I realized that the pain was responding to my eating. It never went away or got down to mild levels, but I could make it go from excruciating to merely unbearable by forcing myself to eat.

The doc wanted to know if I hadn't eaten before the other migraines, or if I felt weak or lightheaded beforehand, but I couldn't remember anything like that, and he thought it might be worth testing my blood glucose levels if they recurred.