Hi You should not ignore even small lesions in mouth. There are many reasons of ulcers in mouth. You should consult your dentist and get appropriate treatment. Do not rub or touch that area. Dont massage that area, even not with any ointment untill you get it diagnosed. It may be due to traumatic lesion, fractured tooth or restoration, due to some reaction from medicine, gastric upset (GERD) etc. its important to eliminate the cause first.

U shud avoid hot spicy and citrus foods in ulcer.  Apply dologel in affected area 15 min before and after food.. Eat soft foods...rice .,khichri,daliya

Buttermilk is not the cause of your problem and is only a factor that has precipitated the symptoms. Rational solution cannot be provided for your query without a proper clinical examination or a look at the clinical condition of the affected area as a photograph. Try to visit a dentist for a proper clinical check up as soon as possible. Regards.

Hello, going by your description, it appears that you gave got infected ulcer in the inside cheek. The ulcer can be because of an accidental cheek biting, rubbing of a sharp tooth or cap or a filling against the cheek, or because of an impacted or partially erupted wisdom tooth. It is advised to consult your dentist and get examined to cure the cause of the ulcer and swelling. It should not be ignored. Pls dont try any home remedy. And pls dont apply any hot or cold packs. T.C