Hi.. Can understand your concern.. As per your complain it seems that your tooth that is paining is deeply decayed and the infection has reached the pulp which is central part of tooth and contains nerves and blood vessels which are carried till the roots through small channel in root known as root canals. Once the infection reaches the pulp pain occurs and the treatment for eliminating infection and pain is ROOT CANAL TREATMENT. In this process the infected nerves and blood vessels are extirpated, the canals are cleaned and shaped using specific instruments and then filling is done from canals till the crown of tooth. If after initiation of treatment there is still pain and lump on gum it means the infected tissues are still present and needs to be cleaned.. Also antibiotics and painkillers are to be given by dentist which I hope you must be advised by your dentist. I would suggest you to consult your dentist again and let him clean your tooth again to clear off remaining infected tissue and provide you with antibiotics and painkillers if not given. Other thing is that you had three fillings, so if any filling is just next to this tooth get evaluated for that too to check if that tooth is hurting. After completion of root canal treatment hopefully you should have no pain at all. Hope your query is solved.. Thanks and regards.. Dr.Honey Nandwani Arora.