Have Oval-shaped Lump Under Left Butt- Cheek.It Is The Size

Have oval-shaped lump under left butt- cheek.It is the size of a prune..not red or itchy and not painful. .has been there for a couple years..it may be getting a slight bit larger, unless it's my imagination..How can I treat it at home successfully?
Thank you for being here for all of us who need answers..
Judy