Does your sister see a Rheumatologist?
Is she on any medications for her RA?
She also might want to see a Gastroenterologist in regards to her gut problems, she may have another autoimmune disease on top of RA.
Sorry she is so unwell, she is lucky to have you to worry about
Let us know how she is progressing.
Current meds: Methotrexate, Prednisone