Long story short..... worked out year s ago until I tore my meniscus (right knee). I visited a Sports Medicine doctor, had a MRI and was told to NOT do the treadmill, heavy walking etc, until it healed itself . I didn t do exactly as I was told however I did exercise less and gained about 40 lbs. I am still active but I do not do as much because I know if I do my knee pain will flare up. The elliptical works great as I do not have (or as much) the knee pain afterwards. I recently started back doing machine weights at the gym and my knee seemed to like it - less pain. About a month ago, I tried a Zumba class and now my knee hurts like crazy. As before, my knee feels swollen and hurts. I am unable to bend it even at a 45 degree angle sometimes. This weekend I stood up for a long period time and yesterday I was pretty much sititng down the whole day because my leg hurt (throbbed in the back of my knee). I am going to go back to the Sports Medicine doctor to get another MRI/ X-ray . What s going on?