I have a constant twitch in my left side of my mouth fir a couple weeks and my theeth are chattering, i am concern ?

Electrolyte problem: Twitching like you describe is often associated with a low calcium level, but could be related to magnesium, potassium or sodium imballance. Thyroid problem could also cause this.

Concerned see Doctor: Uncontrollable spasms or contractions of the muscles around the mouth are called muscle tics or twitches. Some are normal and minor, and may be triggered by stress, a lack of sleep. Other twitches could signal something serious, such as Bell's palsy, where the facial nerve is damaged. Other causes of mouth twitching include muscular dystrophy, damage to the nerve that leads to a muscle condition

In your case: is a sign of anxiety, and one that can cause a great deal of distress. Depending on the cause of your anxiety symptoms, your health care provider can recommend appropriate treatment. See your PCP for evaluation and possible referral.

See dentist asap: Could be several causes, possibly, and should even consider what is called Trigeminal Neuralgia, but a different form. This is an issue that should be seen asap