I hate to disappoint you about your cheek muscle twitching but see the question I am going to post on August 1, 2006. My similar twitching has been going on 8 years!!
Well, I see the posting service is all full up today so I will (as a way of venting) tell you that my BFS started 8 years ago and never went away. It is in form of facial contractions/twitches, normally around eyes, mouth, cheek, or forehead. The symptom location moves and resides in one or more of those areas before relocating to another! Location lasts maybe 4 to 8 weeks. Contractions are maybe every few seconds, continuos for minutes or hours or days or weeks! Not stressed, sleep well, no caffeine, etc. Doctors have only drugs. Tegrotol, Neurontin and now Trileptal. Symptoms at first were cyclical with no symptoms for 6 weeks, then with symptoms for 6 weeks. Cycle got shorter and now I might have only a day or 2 with no symptoms. I work 20 hours/week to get rest and overcome side effects of drugs. Crappy quality of life, money tight, and socially embarassing, not to mention difficult to concentrate at work. No pain but psychological torture. Accupuncture no work. Oh yes, MRI good, blood good, electro tests good. Completely "healthy"
Muscle twitching is common and usually benign. It can be caused by general fatigue (make sure you are getting enough rest), excessive caffeine (look for caffeine in your diet), cold, exercise, certain medications such as mestinon.
Usually it doe snot persist more than a few weeks. Follow up with your doctor though as I cannot give you a formal opinion over the internet.