Could it be a repetitive motion injury?
Makes me wonder when you mention "artist/designer and musician" those are hand & posture intensive uses.

You might want to read on our thoracic outlet forum {TOS} for info on that possibility.
The useful sticky threads are like a crash course of info- all in one place- from the web searches by members.
TOS forum useful sticky - http://neurotalk.psychcentral.com/thread84.html

Most of the forums here have stickys of collected info - they are located above the main threads list with the green circle icon w/arrow on it.

If you are able to describe your symptoms we might be able to help point you in the right direction.

TOS is another of the mystery conditions and quite a few of the symptoms can overlap with RSD.