I have a sore left knee on the inner side i find it worse after bending or crossing my legs for more than 5 minutes what is the cause?

Injury or not?: Questions that could help determine your diagnosis: was there an injury? Do you have swelling? Are you exercising or training for something? How long have the symptoms been present? Is there painful clicking or popping? The medial collateral ligament, 3 tendons, the medial meniscus, the medial joint, a potential plica, medial retinaculum and patellofemoral joint can cause pain on the inner knee.