Pain is the most common manifestation of any internal derangement in any part of the body. Which is true for knee also. Therefore it is impossible to diagnose your knee problem just by the description you have provided. There are hundreds of conditions which can cause knee pain
and we need to diagnose them to formulate a treatment plan. That is possible only by a proper clinical examination together with investigations like X rays, blood tests and scans. See an orthopaedic surgeon
, some how !