Hello,
Thank you for your query at DoctorSpring.com
Do you have any recent history of fever? It looks more like an ulcer, which usually is self correcting.
No need to do any treatment.
Apply xylocaine gel onto the ulcer if there are burning symptoms.
Sometimes these ulcers can be caused by a sharp tooth associated next to this region which is irritating the cheek portion during biting.
If that's the case, the sharp teeth needs to be blunted/ smoothened.
If ulcer doesn't heal within a week's time, better to consult a dental surgeon.

Feel free to discuss further,
Regards