Hi, I think what you are having is what is called a fasciculation. It is a twitching of an involuntary muscle. This can occur from fatigue, illness, stress, magnesium insufficiency, or can occur as part of a disorder called benign fasciculation syndrome.
It's usually not harmful, though it can be very annoying at times.
I've had it before for weeks at a time. It eventually goes away. But check with your doctor. He or she might be able to give you something to prevent the twitching.