I would suggest you see an oral surgeon asap.
Hi Dave,
Is there anything in the area that could be rubbing against the area? Common ulcerations can be caused by irritation from rough fillings, dentures or chips on the teeth contacting the area. Another common ulceration that's painful is an apthous ulcer (canker sore), but they generally heal up by themselves typically after 7-10 days.
Any persisting lesion that does not seem to be resolving should be examined by your dentist or physician for further examination.
Zzzdentist