I can't tell from your log when you ate in relation to when the headaches come on.

One possibility that occurs to me is that your headaches might be occurring when your glucose levels are low, if you are prone to hypoglycemia. You can figure that out by observing if you tend to get the headaches when you haven't eaten for a few hours or more or/and by testing your glucose levels. If that does tend to be a problem, making sure that you have protein or/and some fat with your meals and frequent meals or snacks should help. Also, trying to avoid too simple carbohydrates and sugary foods, which cause glucose levels to spike and then plummet will help.