I used to work in a rheumatology clinic, so the first thing I"m going to recommend is making sure you are working with a good rheumatologist that you trust. I have witnessed what some of our patients felt like when they had a flare of rheumatoid arthritis, so I know that can be an awful lot of pain to handle. Fortunately, there are multiple different treatment regimens available (including some new ones that were approved after my career took a different path).

However, as far as crystals go, I've successfully used amethyst to reduce pain levels. I have osteoarthritis (which is nowhere near as painful as a RA flare, I realize), and I have applied amethyst to my knee to help tone down or turn off the aching.

I have also done my best to "memorize" the energy of amethyst, so that when my hands or my knee hurt, I can create a clear visualization of that amethyst energy surrounding the painful region. That has just the same effect as applying a physical stone to the pain. This is good, because I can't just haul out an amethyst when I'm in the middle of situations that need my attention, like driving. Let's suppose one of my hands decides that it hurts to hold the steering wheel. I can envision it bathed in an amethyst aura, and keep that energy there until the pain calms down. That way, I can keep my eyes on the road and my hands (including the sore one) on the steering wheel at all times.

Good luck. Anyone dealing with a rheumatological disorder gets my thoughts and prayers, because I know that can be a hard row to hoe.