Hi Meir,

 You say the shoulder is affected. Did you engage in strenous movement of
some kind - pushing, pulling, lifting?

 Very often we experience stress on the non-affected side because of
over-compensation due to deficits with the affected side. That said, wear
and tear tends to cycle inflammation of the tissues, which cycles the
spasming.

  I use a bag of frozen peas on shoulders, elbows and knees, and even ankles
if they are over stressed. I keep a bag of peas in the freezer just for that
purpose. Daily Vit C acts as a great anti-inflammatory. Glucosamine might
also address some of your issues. Diazapam aka Valium is something you don't
want to get locked into - it's addictive.

  If this new pain was precipitated by a recent event, then perhaps you are
best waiting it out and taking a short course of script anti-inflammatories
and/or muscle relaxants.

  No more leaping tall buildings :)

Cheers!

Carla