I've had RSD 10+ years, and had surgery a few years after the diagnosis to make sure there wasn't a structural issue, AND only FINALLY lost all doubts to other issues since a Ketamine infusion took away ALL of my swelling for a few weeks. My wrist had just never felt "normal" in all those years, and I've had most RSD issues, but I don't present as a "classic" RSD patient in some ways.

It sures sounds like what you are experiencing is RSD. Having an MRI seems like a great idea just to be safe, since it's non-invasive. Color and temp changes can come and go, which is difficult when they don't happen in front of your doc. Make sure it's documented when it DOES happen in a docs office, and start taking pics as well! Of the RSD side and the healthy side, for comparison.