Hi Marianne and welcome to the RA foirum
Im sooo sorry to hear about your Mother, I hope the treatment she is having makes her cancer-free. Im not sure if you have been on the Breast Cancer forum - if not - they are a lovely bunch who are compassionate with lots of experience to share, so, dont hesitate to go their for advice.
In regards to her RA pain, I would try heatpads and hot showers if she is able - I do this before I get to see the Rheumy to adjust my meds and it eases the stiffness and pain somewhat.
Please keep us posted on how your Mother is doing.
Take care
Jo
ps - I hope the stress hasnt upset your UC - us IBDers tend to flare when we are under strain - take care of yourself - Jo