Unfortunately that kind of twitching/pulsing thing is pretty common and usually no cause is found. Doctors really don't worry about that kind of thing. It's most common around the eye and eyelids, I think.
I had a period a few years ago where every time that I'd stimulate the eye area somehow--opening my eyes very wide, squeezing them shut, sneezing, or just passing my hand over my face, would cause me to get a twitch above my left eye, like clockwork. Then, without fail, a few seconds later, a twitch would start under my right eye. It was very amusing!
Nowadays the mystery twitching is in my cheek off one side of my mouth.
Please don't worry about it too much unless you have other unusual or problematic symptoms.
Nothing comes to mind. See an Eye MD for a real life exam. Find one at www.aao.org
JCH MD