Hi, I Too Leviquin Generic Pills For A Sinus Infection

Hi, I too leviquin generic pills for a sinus infection 2 weeks ago. I went back to work this past Tuesday. When I was walking around the back of my knees started hurting. The muscles behind both knees are stiff & hard to straighten legs at times. What can this be? It's been doing this since I went back to work this past Tuesday. I get up from sitting and the back of knees are stiff & hurt. Thx