Hi welcome to HCMForum. There might be a hair line fracture
of the mandible. or a foreign body would have been pricked and stayed there.
Now got infected and started paining. There is a possibility of getting a swelling also. I advise you to consult a surgeon for diagnosis and
treatment. Dont worry every thing will be fine after treatment. Avoid taking pulses potato and fish to minimise the formation of pus.