Hi..It seems to be a draining sinus from gum which usually is associated with tooth infection. It should get resolved with proper antibiotic course and root canal treatment which you are already undergoing. It takes more time for healing but finally it should go good. Regards

From your description tooth seems to have a draining sinus usually depending upon the extent of infection diagnosis and treatment planning is done a clinical checkup with xray evaluation is necessary to come to a conclusion. '

Hello. There seems to be an infection. This could be either be a tooth-infection, or a gum-infection. First thing your dentist will do is to find the source of infection. The treatment will be planned accordingly. At times, frequent visits are required on a regular basis to take control over the problem. It would be of some help if you can upload a photograph of the tooth &/or it's x-ray (if you have one). Take care.