Since the pain and snapping sound and feeling of strain is persisting for a year, please consult your doctor. Since there was a kick at the back of the knee, you could be suffering from 'popliteus tendinitis'. The other such inflammatory tendinitis conditions giving pain at the back of knee on inner or outer side (along with possible ankle joint pain) are Hamstrings tendinitis and Gastrocnemius muscle tendenitis. Another cause of popliteal pain is injury to the posterior horn of lateral meniscus. Please consult an orthopedic specialist regarding this. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.
Thank you very much, I highly appreciate it.