Hi. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain swelling in the area you described is swelling of the lower labial frenulum and it can be due to any injury caused by either the toothbrush or any hard food which must have hurt the frenulum which is a delicate structure and caused its swelling.. There may also be the formation of a traumatic ulcer or can be the beginning of a Canker sore leading to pain and swelling.. You need not to worry as it will resolve in a time period of almost a week.. You can apply a numbing gel like Dologel or Oragel over the swollen area for relief.. Apply a steroid based ointment like Kenalog in orabase for reducing inflammation and swelling.. For pain anti-inflammatory painkiller like Ibuprofen [advil or motrin] can be taken.. Sucking ice pops and cold water gargles can help in reducing inflammation and pain.. Use a soft tooth brush to brush your teeth and also brush your teeth gently.. Avoid hard and spicy food to prevent irritation in that area.. Hope this information helps.. If you find the answer helpful please give me a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora..