“Should I worry about the twitching of my eyebrow?”

This is due to nervous excitability of the dense collection of nerves activating muscles of the face. It in fact has a medical name: myokymia. It is somewhat common in folks in the middle years. It is benign and will not cause harm although it is sometimes annoying. Usually it is subtle and is felt but not observed by others. Occasionally larger muscle groups are involved and others can see the twitching. Most stop it by rubbing the area twitching but recurrence is the rule for a while but eventually it will stop. A few have reported that eating ice cream or sucking on ice cubes can stop the twitching. Rarely it is so annoying and obvious that the patient wants something done about it. The remedy in this rare occurrence is to inject Botox into the muscle groups doing the twitching. But again, this is a last resort for this completely benign condition.

Usually not. It is due to hyperactive nerves and muscles. Caffeinated drinks may cause this. See a Dr if you experience paralysis of facial or other muscles.