Clunking Noise Pain In Shoulder Clunking Noise?

Clunking noise? - clunking noise pain in shoulder

I have a Mercury Sable 95, began to make a crack when I began this morning. This works very well, only obnoxous makes noise (a sort of reminds me of a lot of cans clunking around). Only when it came to a standstill, and the first time when the accelerator pedal through. It makes no noise when I walk down the street.
No idea what causes it?