Hi
Welcome to the MedHelp forum!
Birth control could be a reason for intermittent bleeding after sex. The various other causes for vaginal bleeding after sex are injury and friction (this you rule out), STDs like Chlamydia, gonorrhea, and trichomoniasis, cervical polyps, yeast infections, non specific vaginitis, endometriosis, cervical dysplasia which is a precancerous condition, uterine polyps, uterine fibroids and cervicitis. None of them are conditions that should be ignored. Since a confirmed diagnosis cannot be given on net please discuss these possibilities with your gynecologist once and get the required tests like internal examination, PAP smear, vaginal swab test for STD, and ultrasound.
Take care!
I'm on Yaz. How long do you mean by "a while" though?
Also, to clarify, when I said it goes away "pretty quickly," sometimes it can be less than half an hour, and sometimes it can be almost a whole day. That's the weirdest part, I guess... just how unpredictable it is.
Stop having sex for a while and see if that's the problem. Perhaps your inside tissues need to heal. If that is not the case then keep notes of any other symptoms. What birth control are you on? Maybe they're the side effects?
You could have unhealed injuries from your boyfriends fingernails that are getting aggravated when you do have sex