Hello.
Thank you for your query at DoctorSpring.com.
The recurrent bump you have is a sinus opening. Sinus is an abnormal tract/ comminucation. You seem to have such a sinus between your molar tooth cavity which is opening out on your gum. A sinus can form when there is an infection in the associated tooth.
You need to consult your Dentist and get an X-Ray done for the tooth with the crown. It may require a root canal treatment, if not already done.
If a already root canal treatment has already been done, it means that the tooth is re-infected and requires re-treatment or even complete extraction, if that tooth is severely infected.
Usually the sinus opening heals once tooth is treated or removed.
Feel free to ask queries.
Regards,
Dr.Girish PV,
Consultant Orthodontist.