HI, thank you for helping your mom through this. Love when family gets involved, support from those closes to us is so important. My thoughts and things I do or have tried that I did not see in the articles or mentioned yet is; TENS Unit, Heated Massage, Ultrasound Therapy and some of those old fashion at home tricks like a heating pad, Ice packs or combination. I prefer moist heat, easily obtained by using a Kitchen towel, getting it wet, wringing it out and microwaving for a couple minutes, being careful not to let it set directly on bare skin for it's hot. As for some gentle but very worthy type exercises, there is "Chair Exercises" many types found on youtube.com an old PBS show called "Sit to be Fit" also on youtube is great, use these regularly for I am unable to take medications that is being offered for RA do to other medical issues, but knowing the activity is good for me and keeps my moving. Diet changes could be helpful. There is foods that promote autoimmune and inflammation control benefits and there is those that can cause inflammation. These usually run in the Fruits, Veggies and Nuts, that will take a little bit of googling can help find those for you, for Brain Fog is happening tonight or I could give you some ideas of those.
That's all I have to offer at this time for help, but do send warm wishes and soft hugs to you both.