Accept osteopathic manipulation and chiropractic correction.
Stand in front of the mirror and see if there is any change in facial muscles. If not, cover your ears and lean back for two or three minutes, three times a day.
Don't pinch the phone, it will affect the balance of muscles on both sides of the neck. Whether they are in a straight line, find out where they are skewed, and look at the chin to the laryngeal nucleus to the midpoint of the clavicle, with the head slightly tilted.
The most likely reason is that the cervical vertebra is injured and dislocated, and the lower lip smiles slightly to one side.