Mother has knee pain and swellingin body

Mother is having slight swelling in whole body. She also has knee pain since 20 days  for which she is taking hifenac-mr tablet when pain increases  . After taking medicine she is able to walk properly and feels good for 1-2 days.( In the year 2015 she was having knee pain and back pain for which we did xray and report said that she was having gap in knee and back after that did physiotherapy and took medicine then she felt good but sometimes the knee and back pain used to occur again in a duration of 2- 3 months approx ) . she is also facing with slight pain in lower sideways of abdomen.abdomen pain is from 2 days and  got some relief from applying hotwater bag in pain areas in lower abdomen and drinking hot water. Please suggest , I will be thankful to you .