Your description describes a chronic dental infection pertaining to the affected tooth. The lump may be a draining sinus which won't go away unless the tooth is treated. You may have to consult an endodontist to perform a routine dental procedure called Root canal treatment (RCT). Kindly do not wait, seek professional dental help asap. Hope this answers your question.

Thanks for your query, I have gone through your query.
The lump in the neck could a periapical abscess or a enlarged regional lypmhnode secondary to the gum or tooth infection. Since you are giving history of the guma and tooth pain, consult a oral physician and get it evaluated, take a radiograph to rule out the gum or tooth infection.
if it is gum infection get the teeth cleaned once and maintain oral hygiene after that. You can use mouth wash.
if it is tooth infection get the tooth restored with RCT.
I hope my answer will help you, take care.