Umm, from bike to bike :P :P .
I've done the same thing to my shoulder before, but the muscle was torn in the end :P , only fell off the back of my brothers bike. At first it burned, then it was just pain :) . I'd say go to the doctors and get some deep heat (muscle ointment stuff, probably avaliable at chemist :( ) to rub on it :P .
Cheers,
Josh.