After going through the case history you have given it might be either the root piece ie.,part of
teeth left out inside or may be a bony spicule ie.,sharp edge of bone popping out.
In either case its better you visit the dentist
If its a root stump better get it removed ,and if its a bony spicule it will be smoothened or the
sharp edge will be removed.
Hope so this will help you out.