Hi.. Can understand your concern.. As per your symptoms and location of swelling it seems as if the swelling that occurred is the swelling in Parotid gland which is one of the major saliva producing gland of the human body. When we eat food during that time the saliva production from glands increases and when there is any obstruction in the ducts which carry saliva from the gland to mouth the saliva goes back to gland and starts collecting there due to which the gland starts expanding in size leading to swelling. There may be a number of reasons of obstructions like stone or calculi formation, infections and inflammations of ducts, injury or trauma to the gland ducts. In case of obstruction the swelling is increased during eating and gradually reduces when eating is stopped.. I would suggest you to consult a doctor and get evaluated fr the exact cause and nature of swelling so that a treatment plan can be made and executed. Hope you get well soon.. Thanks and regards..