Knee pain and bruising on knee

Patient: I am 13 and I play softball, volleyball and basketball.For basketball Iam on a triple crown team and play 4 basketball games evey week. One after another. I have had really bad knee pains in my left knee since I was 9 and have had many injuries. I wear a knee brace but it always is pretty bruised after a practice or game. The pain usually accures on The Inside bottom Part of my knee cap. I’ve talked to some people and they said it might be a muscle but I’m not sure if I should be worried about it or not