We’re sorry to hear about your staining.
Not all stains render a woman niddah. While we cannot universally ignore stains, there are certain stains which halachah stipulates do not cause niddah, and do not interrupt or invalidate the seven clean days. In your case, where you are in the clean days and wearing white underwear, two leniencies are most relevant. If a stain on underwear is smaller than the size of a gris (roughly, the size of an American dime or Israeli shekel), it does not invalidate or interrupt your clean days (although there is no minimum size for a stain on a bedikah). If the stain does not have a reddish hue, it does not invalidate or interrupt your clean days.
Bring any stains on undergarments or bedikah cloths to a rabbi for assessment. Do not assume that they are problematic; have them evaluated. If you still cannot get seven clean days, contact us or your rabbi about reducing your required number of bedikot.
We recommend reading our article on stains for more details. You may also wish to change your underwear frequently, which may help reduce the odds of a bigger stain.
Staining within the first few months after IUD insertion is fairly common. If the problem does not get better within a few cycles, we suggest consulting your physician. If you are using the Mirena IUD, however, staining could persist for up to six months. At that point you would probably cease to bleed at all.