If your pain is below the knee on the inside part, This can be inflammation of a bursae in the knee, condition called as Pes anserinus bursitis. It is a curable condition by physiotherapy modalities and further by stretching and exercises.
Next Steps
meet a good physiotherapist to get the inflammation relieved at the painful site.
Health Tips
if swelling is present take ice pack locally for 5-7 mins for 4-5 time everyday.