How To Treat A Small Painful Lump In Knee?

There is a small lump in my knee. When I walk dow the stairs it tends to roll out to the inside of my knee so that way I can feel it and move it around. I can manipulate it so that it goes to somewhere else in my knee. It can pop out at other random times as well. The lump can hurt when pressure is applied but it is always annoying. Also my knee is swollen is restricted when I participate in physical activities. Can you provide me with some help?