I was on Levaquin for chronic bronchitis several times without reaction and then had to take it for 20 days for bronchitis that just wouldn't go away. Starting the 5th day I experienced severe joint pain (worse than my current fibromyalgia pain) and swelling in my feet and ankles. My physiotherapist suggested that I take Kefir once the antibiotic ended to clear out my system. Apparently the bacteria in it counteracts the side effects of Levaquin. It worked for me and I'm only experiencing my normal pain now and my feet look normal again!