I tore my meniscus in my right knee two years ago playing basketball but, it has not completely healed. I cant do a full squat and i lost nine inches on my vertical jump (I'm down to 14) i also have some tendinitis in my left knee. After four hours of sports my knee swells and stiffens and is no longer mobile until i sleep it off. In the past year i have discovered a big bump on top of my right knee so much so that when i bend both knees it is very noticeable protruding from the front of my knee.
The two conditions are probably unrelated. For your knee it sounds as if you may need to have it operated to remove the torn piece of the meniscus. The meniscus doesn't have good blood supply and so it doesn't heal well (if at all). Have an MRI done on the knee and see an orthopedist to discuss your options. Does the bump on your knee hurt and is it soft or hard? If it is hard and if you are young it could be Osgood-Schlatters disease / Syndrome but there could other reasons as well. Have it looked into.
Good luck