Hi.. Can understand your concern.. As per your complain sudden swelling below the right jaw and which is specifically noticed after drinking water and eating lunch Can be due to obstruction in the duct of right Submandibular salivary gland.. The obstruction is caused due to formation of Sialoliths which are crystalline stones formed from minerals in saliva.. When the duct is obstructed there is backflow of saliva to the gland causing swelling which is more during eating and drinking as the saliva flow is more in that time.. I would suggest you to take more of sour candies,lemon drops and sugar free chewing gums as it will stimulate more saliva flow and small stones tend to flow out of duct and duct is cleared.. In case if it doesn t happen you need to consult a dentist and get evaluated as stones may need to be removed either by palpation over the stone and pushing out of duct while large stones need surgical removal. SIALOSCOPY is an endoscopy technique used to locate Sialoliths in deeper locations and subsequently removed.. Hope this information helps.. Thanks and regards.. Dr.Honey Nandwani Arora..