What Happened to My Head?

I woke up this morning with a horrible, throbbing pain on the left side of my head.  Not like a headache, but like I'd been struck with something.  Really hard.  What the hell?  When it didn't go away, I reached up to investigate and found something disturbing--a huge bump!  The circumference is about that of a standard salad dressing lid and it's raised about a centimeter off of my scalp.  The bump itself isn't really out of the ordinary, but the fact that I have no idea what I did or when I did it really freaked me out.  I woke George up.

"Bean!  Wake up!"  He rolled away from me and snuggled deeper under the comforter.  "Bean, seriously.  I need you to feel something."

"Not right now, I'm still sleeping," he half mumbled.

"No, there's something wrong with my head."  Somewhere between irritated and amused ("Don't even say it!") he finally sat up.  I took his hand and pushed it to the bump.

"What the hell did you do?"

"I don't know.  I just woke up and it was like that."

He couldn't see much through all of my hair, which is disappointing because I really wanted to take a picture.  I have a weird thing about thinking others are as fascinated by my wounds as I am, especially ones that can't be explained.  If I'm going to hurt myself, I should at least be able to share that with the internet.

I eyed George suspiciously.  "Did you hit me with something while I was sleeping?"

He just rolled his eyes and went back to bed.  I still have no idea how this happened.  I considered the possibility that it happened last week, when I thought I could drink like a college student, but surely I'd have noticed it before now, so I don't think that's the case.  Or maybe I hit my head hard enough to not remember hitting it, but then, that would have merited a trip to the emergency room, at least, and I like to think I'm not that negligent about my health.  I can only think of two other possibilities:

1.  George did, in fact, hit me with something while I was asleep.  There's no motive (other than the fact that I think it would be really funny to hit me with something while I'm sleeping) and I can't think of a single way that would benefit him, but I can't rule it out completely.

2.  The stylist did something under the guise of giving me an outstanding haircut and I was too distracted to notice.

Actually, now that I think about it, there's a third prospect, and it's the most likely.  Pie did it.  I don't know whether it was on on purpose of accidental, but I'd be willing to bet it was Pie.  What I can't figure out is how I didn't wake up.