I was thinking about how to describe RSD in a way that someone can visualize. Heres what I came up with:
There's a dragon living in my arm. Its scales are made up of broken jagged glass and razor blades. Sometimes, the dragon is quiet, only moving restlessly in its sleep, breathing its steam breath. Even just by being present, the scales dig and rip at me...the restless dreaming is the best I can ever hope for. Then there are the other times, when its active, twisting and turning, its tail wrapping around my wrist or shoulder or elbow, and then dragging its tail away. It breathes fire everywhere, and it feels like every where its scales and claws are, my arm is being torn, ripped. This is my 'normal'.
Then there are the really terrible times. The dragon is angry about being trapped in my arm and wants out. It writhes in fury, clawing, biting, ripping and tearing, while trying to set fire to burn its way out.
These sensations are so real that I look at my arm, expecting to see the jagged glass trying to push through my skin.
Thats the most visual way I can think of to describe what living with RSD is like.