Im 21 yrs old and i have this recurring knee pain on my left leg.it started after doing some jumping exercises and its been months the pain comes n go?

Go to see MD: You need to go to see your md to get checked. You could injure/tear your ligament/s or other soft tissue on the knee. Need more evaluation. Meanwhile, you can help yourself-by putting some ice packs, nsaids, elastic band/knee cap protection and don't do too much jumping exercise that may make it worse. Go to see md and check it out.