You can't really diagnose anything yourself but I found an old test that was sometimes used to check for RSD online. Obviously I don't know if this would be positive for other conditions and doubt it always works for RSD.

You just put a little isopropyl alcohol on the hand or whatever and see what happens. When I do it I get a rapid increase in pain. Even water evaporating from my hand will cause pain so I have to dry it immediately. I get a little pain just thinking of putting alcohol on it.