Metronidazole vaginal gel ?? Help!!

Im 31 weeks, I went to my doctors appointment 3 days ago and he prescribe me metronidazole cause I was having yellow discharge. Now that kind of discharge is gone, but I notice a white cottage cheese like stick to my vagina, it don't come out when I go to the bathroom, i just felt it when i was taking a bath and then look down there with a mirror and its stick there. Anyone had this? Is just the medicine working? A Side effect. Or what it could be?