Hello, I Hurt My Buttocks Almost 5 Years Ago Accident

Hello, I hurt my buttocks almost 5 years ago accident blunt trauma. When I saw a dr, she said it was bruising and will go down on it own. Now there is a lump that remains on my right upper buttock, not painful but annoying because you can see through clothes.
Can you please recommend how to get rid of this?
Many thanks!