swollen right calf and foot

Hi, my mother is 52 years old she suffers from rheumatoid arthritis and it is currently in treatment to control the pain. Every 4 to 5 weeks she gets remicade and has to take methotrexate for the treatment to work. Also, in order to keep any flare up pains away she occasionally takes advil, darvocet, or celebrex (not all three together). On saturday her right leg below her knee started to swell up and yesterday it was not only the calf and leg that were swollen but her ankle was swollen too. Today we went to the doctor and he sent her to get a dopler scan to see if there were any blood clots. She got the scans and there were no blood clots found. The lady who was doing the scan said that she saw a lot of fluid coming out of her joints and asked me if my mother had arthritis, which i confirmed. Now my question is what should i do now?? If it is not a blood clot what is it? Also the leg is not heavy or painful, the calf hurts a little when you touch it and thats all. My mother said that like 20 years ago she had a kidney infection and she was wondering if that could be it, but can a kidney infection induce swelling of one leg only? Please tell me anything you think it might be and what should i do?
Thanks
Any advice is greatly appreciated

[remar]

My sister also has rheumatoid arthritis and has gone through this. It sounds like your mother does need to get blood work done. Has he Dr ever mentioned putting her on water and potassium pills?  My sister has had to use this treatment a few times for the severe swelling.  Please keep us up to date on what her Dr says.  Remar

[tazkari]

thanks so much, i will