This symptoms are indicating towards a knee condition seen in young age called chondromalacia patellae. It is due to friction of knee cap with the bone below. It’s completely curable condition. Having said that lower back nerve compression causing pain in knee also needs to be ruled out.
Next Steps
Kindly visit nearby orthopaedic for management of pain and accurate diagnosis. Further to which physiotherapy would be required for complete recovery and for preventing relapse in future.
Health Tips
Take rest. Apply ice pack for 15 mins on the painful knee. Avoid prolonged bending position of knee. Avoid running till the pain is tackled.