weakness in both legs

miss maggie

I have stage 1, low grade, b cell Non-Hodgkin Lymphoma. I had treatment once a week for 4 weeks of rituxan in dec 2009. No side effects at all. Now it is march 2010. At the end of feb I started having weakness in both legs. I have no pain, but I get very tired in both legs. I did have a flare-up of pain in my left knee. My doctor gave me an injection of cortisone in the knee, and that helped alot. I get so tired, and unable to walk far. I was always a walker. Is this related to rituxan. Thanks for any input. Maggie