Cheeks generally refers to the chin on both sides of the cheeks, eat the first mouthful of food on both sides of the chin cheeks acid may be salivary gland stones or temporomandibular joint disorder disease caused by the following. 1. Salivary gland stones: If the stones are large, the gland will swell when eating, and the patient will have soreness or pain, which can radiate to the ear, temporal part and neck. The pain may radiate to the ear-temporal region and neck. The discomfort may disappear about half an hour after stopping eating. 2. Temporomandibular joint disorder: masticatory muscle pain may appear when eating, which may be accompanied by joint popping, broken sound, murmur and different degrees of opening restriction. Eating the first meal on both sides of the chin cheeks acid may also have other reasons, it is recommended to go to the hospital in a timely manner, clear causes for targeted treatment.