Hello,
Most likely it was developing all along , and some thing put it over the edge..

How is your upper body posture? head /shoulders forward, hunched or rolled forward? That might be a part of the cause along with the music.

I will suggest you explore our Thoracic outlet syndrome forum (TOS) for short...
May or may not be the cause for you, but we have a lot of additional info and therapies that can be helpful for repetitive use injuries also..
Here is the useful sticky thread to get you started..
http://neurotalk.psychcentral.com/thread84.html

You may want to read about double crush & triple crush w/ TOS if you continue to have symptoms or they return in the future..