Silly story, but here it is. My right knee swelled. I went to Medline Plus (**reliable** medical info from the National Library of Medicine, people.) Read about meniscus and ACL tears. Imagined the worst. No more Zumba. Turns out it was just my knee complaining of overuse. First sports injury of my life caused by over-exercise. I'm actually celebrating! (as I look for some gentler activities to alternate with Zumba)