It's much more likely that you hit a nerve. This should be a very isolated incident, but as the saying goes, be careful out there!
ess
It would definitely cause a reaction, but I have never hit a muscle..or I don't remember it.
And yes, I could forget..did you put an icy cold pac on it?
Its definitely a adventure when you start copaxone, I have been on it for over a year now and it is starting to get easier and less reactions. It less time for some though.
Good luck with it...
meg