why am i so sore from wrking out?!?! i try to go to the fitness center 3 to 5 times a week! but i seem to get sore around my pecks!!!!! even if i do lots of stretches!

and......... is creatine ok to use?!? lots of people told me its sweet stuff and i am on the verge of buying some! and if so is it very effective or not worth the shit on teh bottom of my shoes?