Hi. I was walking moderately at the park, but at the end of the walk, I needed to use steps to go to my car. The first step or two, I felt like I either sprained or strained my left knee/behind knee/upper calf. There s no swelling just very sore when walking, bending, etc. This happened on Friday. I ve been resting, icing, and elevating the leg/knee. Please advise.