I have just finished some treatment following extraction of 3 molars 10 years after treatment. The extractions created necrosis but I realized that bone loss, minimal saliva production, and loss of blood flow create problems that can surface at any time in the gums or jawbone. I would recommend seeing a specialist and start a diagnosis. This does not happen for no reason or clear up on its own. (Mine were pulled without guidance from an ENT or other specialist to my regret)