What Causes Painful Lump Inside Knee?

I have been able to move a lump around my right knee cap for a few years now, it is soft & occurrd after I busted my knee open running up stars when I was little. pressing on it would cause pain but that s it. I recently discovered a small hard bead like lump under my skin on the same knee that I can also move and hurts with pressure. I play volleyball so am constantly falling on my knees hard but don t know what the lumps are or if I should see a doctor?