It's homework. It's supposed to hurt. It's like a portable prison you can set up anywhere and become magically trapped, bolted to where you sit for hours.
But seriously, I don't know. It's usually something simple that you don't realize until somebody says something. Drinking enough water? Had too much caffeine? I remember sensations like that sometimes when I was in college pounding pots of coffee. Sort of an anoxic, acidic, drowning feeling - like I was at the bottom of the amazon for a few moments. One day somebody was telling me I seemed too caffeinated. They were right!
Steak, eggs, potatoes - fruits, nuts, berries and forage. Coconut milk and potent herbs and spices. Tea instead of coffee now and teeny amounts of kelp daily. Let's see how this does! Not really had dairy much, and gut seems better for it.