Hi
From your symptoms it is clear that you have pain in left knee mainly when you fold your leg and there is no pain on climbing stairs or walking. You also have occasional pain in your finger joints.
Symptoms mentioned by you are non-specific and it needs further detailed history. I would advice you to take appointment for consultation for detailed findings and accurate treatment.
Next Steps
Consult directly with me, your orthopaedic doctor, through Practo for detail history, discussion and treatment plan. Here we can chat or can also do audio or video consultation for detailed management. Take appointment for thorough prescription and consultation
Health Tips
Avoid squatting, sitting cross legged. Do hot fomentation. Do exercises for quadriceps and hamstrings.