I think it’s safe to say:
I WAS NOT EXPECTING THAT!
At first, you build up this rapidly increasing tension, a mystery around the “incident”, and (I don’t know if anyone else reading this assumed the same thing, but) the possibility of the character committing suicide because of these headaches.
But ending it like THAT?!
It’s like when Dan Akroyd ripped off his human face to reveal his monster side, in “The Twilight Zone Movie”.
So, seriously, well done on managing to shock me to the point of gasping audibly, and raising my eyebrows to their highest limits.
=)))

The last sentence took this from being a psycho/serial killer type story, into being more toned down comic book/hulk type story. Either way, it was good

Thanks for the comments! I wanted to move away from a psycho killer idea, just because it’s tough for me to get into that mind space. I don’t know why I went with the hulk out role, (which I feel is probably a more apocalyptic role than the hulk), but it seemed that, to me, that’s where the story was going.