Muscular spasms and twitches are generally caused by a lack of salt. If you had worked up a good sweat playing footy, then didnt have something isotonic, that would be a pretty good reason for it.
When you say Footie you mean american football right? If you were using your right arm a lot to throw (if you were QB) then that would be the explanation.
As to the mental process - I would also have gone Razor, Blood, Face. Probably then with a quick look to make sure I didnt damage the bathroom surfaces, because that would have been the girlfriends first thought.
Si