Hello there...There are two things to this....Firstly, that could be a fibroma/mucocele
. Mucocele would have a bluish translucency. Whereas fibroma would appear in the normal color of your mucosa. Both of them are soft to firm to feel on palpation. Both of them occur as a result of local injury
or some irritation to that area.
Secondly, any carious tooth present in that area would lead to small swelling that is attributed to spread of infection from the top surface of the tooth to the apical part resulting in collection of pus. This would manifest in the form of swelling. The Endodontists are experts in handling a carious tooth that would require root canal treatment
. If the swelling is for the second reason , if root canal is performed the swelling would recede. If the swelling is because of the first reason I gave you, consult a Oral and Maxillofacial Sugreon for its removal.