"Get your eyes checked, at best you get told you have 20/20 vision and you're mad, and to drink more coffee. At worst you're in line for glasses"

I'd turn that best/worst around. Glasses are easy to get, cheap, and work deterministically and measurably. If you have 20/20 vision and still have headaches, you probably have bigger problems than the relatively minor nuisance of wearing reading glasses.