Possibly you are suffering from runners knee
. Its probably due to Overuse. If you do a lot of repeated bending or high-stress exercises, such as lunges or plyometrics, they can irritate your knee joint, A direct hit to the knee, like from a fall or blow. To treat to: Give rest to your knees, place ice packs over knee to reduce inflammation, elevate your limb, compression .Wrap your knee. Use an elastic bandage, patellar straps, or sleeves to give it extra support.
Take NSAIDs, like ibuprofen
. These drugs fight inflammation and help with pain and swelling
. You can consult an orthopedic for the same.