WHY, BRAIN TISSUE

I think the thing I hate the most about headaches (which I get pretty infrequently) is that they happen for no reason. Obviously I'm not counting hangovers, or the headaches I can get from inhaling newspaper-smell too deeply, or motion sickness, or etc etc. I mean the ones that come out of nowhere, like the one I've got right now. Why is this occurring.

Time to stomp on it with ibuprofen.