Hi.. Can understand your concern.. As per your complain a movable painless lump under the chin can be an enlarged lymph node which must have occurred due to any infection in the teeth or the gums or other parts of the face or any other part of the body.. Many a times an infection in any part of the body can be seen in a distant lymph node as the lymph draining through the lymph nodes in the area containing some infection can carry infection while draining through a distant lymph node.. In that case the bacteria or other pathogen may get settled in the distant lymph nodes and cause infection and inflammation leading to swelling.. It can also be due to obstruction in the duct of sublingual salivary gland present below the chin due to formation of stones from the minerals present in saliva causing resistance in the flow of saliva from gland to mouth and leads to backflow and accumulation of saliva in the gland leading to formation of a lump but it is not freely movable mostly.. I would suggest you to consult a dentist and get evaluated and in case it is a lymph node antibiotic therapy to clear off infection can be helpful.. In case of the salivary gland obstruction removal of the stone can be relieveing.. Hope this information helps.. If you find the answer helpful please write a positive review and click on find this answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora.