What Causes Brown And Yellow Discharge With Bad Odor While On IUD?

ive just recently started experiencing a brownish sometimes yellowish dischrage, at times it kinda gives off a vinegar smell....i know that sounds strange but its becoming a concern. Im currently using the copper iud for bc and i dont have any other sexual partners other than my husband....im a bit confused as to why this is hapening? im wondering if my iud has anything to do with this discharge....