Hi. Dr. Rynne, My Name Is Linda. I Am 66

Hi. Dr. Rynne, My name is Linda. I am 66 yoa with arthritis in both knees. my current problem may be related. About 2 months ago I was getting up from the couch and something on the side of my right calf popped and I couldn't walk well for a couple of days. I thought I might have twisted the tendon. Some days are better than others, but I'm still having a lot of pain. Is this common to a twist or is it possible I have a torn ligament?