What Cases Blood In Vaginal Discharge After Unprotected Intercourse?

i gave birth exactly a month ago, i had unprotected coitus w/ husband yesterday without knowing that i can become pregnant again in that case, i start my contraceptive pills an hour after coitus, could it be prevent pregnancy? And i have vaginal discharge yesterday but not sure if it still my postpartum bleeding or my menstruation, and noticed that there s a streak-blood stretchy mucous.. im anxious about the possibility that im ovulating and might become pregnant again,, is that possible that my mucous was cause by ovulation even there s a streak of blood in it?