Ended up with another headache today. 
Mostly due to spending like four or so hours staring at Yu-gi-oh cards, shuffling through them.
But the hot dry heat that I'm not as used to, and the lack of food and water during that time period probably also influenced the pulsing ache that moved up behind my eyes.

As a bit of time lying down, some meds, and food & water definitely helped it to go away. Woot.