4 months pp. i have been getting thick yellow discharge. i had an iud placed and then removed when it embedded in my uterus back in march or april. test from gyn showed overgrowth of group b. still getting discharge after antibiotics. what could it b?

It's often difficult to diagnose the specific cause of vaginal discharge. Colored discharge suggests infection. Keep working with your doctor. Or an ObG who specializes in infectious diseases; there are such experts in most major metropolitan areas or academic medical centers. If at possible STD risk, get tested for gonorrhea, chlamydia, trichomonas, and maybe Mycoplasma genitalium. Good luck.