I am 49 years female weight 61 kg, height 5 feet. Suffering fron right knee pain for 8 years approximately. I am taking 1 tablet shelcal os and 1 tablet revital women daily after dinner on my own. I consulted doctor few years back he did xray and it is alright. Previously I feel pain when climbing stairs but now I am feeling pain when I go to evening walk too. Should I continue my walk and yoga. I go to evening yoga classes too. Please advise which medicine should I take and what is the reason of pain. Thanks.