What Could Cause Twitching At The Corner Of My Mouth A Few Minutes After Smiling, Persisting For A Year Despite Taking Vitamins?

Hi! i am a 28 year old female. The left side of my cheek (baisically the corner of my mouth) twitches a few minutes after smiling hard. I have this problem since an year. The twitching hasn’t spread anywhere else in the face. And triggers a few minutes after smiling. I had been to the doctor once. He pretty much had no idea about the condition and suggested me some multivitamins and electrolytes. But condition did not subside even after taking the vitamins. Am a working women with no medical history and pretty much try to maintain a healthy lifestyle. Am really worried for my condition. Kindly help