Suggest Remedy For Painful Lumps On Knee With Soreness

Hello, my name is Blair and i am 14 years old. I play varsity basketball for my hometown. Recently i have had to sit out of practice due to pain in my left knee. I dont know what caused this pain, i woke up one morning to soreness and it has gotten tremendously worse despite icing and heating. There is also a hard lump below my knee cap. It hurts to put my weight on it while standing. It also hurts to jump, cut hard, run, ect... What is the cause of this pain? How can it be cured?