Ay sis, same concern ng ilang mum friends ko, yung smelly discharge at brown spotting is actually pretty common sa IUD, but dapat talaga check mo yun with your OB before January 31 if it's really bothering you kasi BV can happen and needs treatment. One of my friends got BV from her IUD, treated it, and it came back twice, frustrating talaga, so she switched to hormonal pills na, pero iba-iba talaga ang body response ng bawat mommy, so hindi one-size-fits-all ang solution. The good news is BV is very treatable, and marami pang options like pills, implants, or even condoms + pills combo kung hindi ka comfy sa IUD, honestly, at 20s with 2 babies na, you have time to try different methods and find what works best for you at hubby. I'd say message your OB sooner if you can, walang waiting till January 31 especially with discharge na may odor, kasi peace of mind na rin yun para sa family planning decisions mo!