What Causes Vaginal Bleeding After Having Sexual Intercourse?

Hi, I wa having sex this afternoon with my boyfriend and we got rough and he went very deep until he was touching the back of my vagina and I heard a pop sound. And ever since then, there has been a slight burning pain through out the day an now I am in the bathroom it s 9:30 and I notice blood on my underwear and I am dripping blood in the toilet and I m scared. It s not a way lot but it is a concern. I am pretty sure this is not my period, I have poly cystic ovarian syndrome which causes me to not have my people very often.