Your symptoms suggest intrarticular soft issue pathology.
Try:
1. Regular knee quadriceps exercises ( static and knee bending).
2. Ice pack application will help
3.Medications like Tendocare and Enzomac forte will help.
Next Steps
If you have instability or locking then you might be having a ACL or meniscus tear .
Health Tips
MRI will be really helpful to diagnose the problems inside your knee joint.