I have finished 4 infusions of Rituxin for Waldenstrom's Macroglobulinemia, a rare form of lymphoma. During and after treatment I experienced severe back problems and pulled muscles. I had no back problems before treatment. Has anyone else experienced these symptoms while using Rituxin? After 6 wks of physical therapy 3 times a week I still can't be on my feet more than a few minutes due to back pain. Would appreciate hearing from anyone with similar experience. Thanks.