Hi. i have knee pain after i bend my knee and then extend it, and it also hurts whenever i play sports. or put to much pressure on it? what do i have?

Needs evaluation: Knee pain is tricky especially if you are young and athletic. Although breaking bones can happen usually it is the soft structures like the cartilage, the ligaments, the tendons that can cause pain when bending and extending. I would suggest a face to face exam. Your doctor can then recommend the proper test which may include an X ray or an MRI. Good luck.

Hard to say: There are many moving parts in the knee. If you have a lot of swelling, it may mean you tore the meniscus, the padding between the tibia and femur, or you might have torn a ligament. But it could also be a minor contusion (bruising). You will not know unless you see an orthopedic doctor who will do an exam and may or may not order an MRI which is the best way of seeing looking inside the knee.