Right knee sprain while dancing.t

Hello. I had a knee sprain back in October 2016 while dancing contemporary( took one month break from it) .After consultation and medication( X-Ray showed nothing, so doctor confirmed that its a sprain), the pain subsided but some stiffness remained ,as in while bending in the knee completely , so that it touches the thigh, some pain was still there and then my physiotherapist told me that the muscles in my right thigh have become stiff and gave certain exercises to do. Till now, my knee got sprained 3 more times in the same place and it pains like it did initially but reduces after half an hr. Now the problem is, while bending my knee I feel the pain beside my right knee cap and exactly below my knee cap ,everyday since the injury. Also, while walking continuously for 10 min, a certain area beside my right knee becomes stiff and painful and it releases itself after sometime and I feel like some knot or tension got released and then its okay for the next 3-4 min. So this stiffening t