Hello,
This bleeding during sex could be from some minor trauma. Did it seem like the sex was at all rough? It is also possible you could have some type of infection or cervical condition so if you have not had a recent checkup with your gynecologist, you should do that now. Even if you have been in recently, if this continues you want to check it out to be sure it is not something that needs treatment such as bacterial vaginosis, sexually transmitted infection, yeast, polyps, fibroid tumors or inflammation.
If the symptoms persist then you should get a thorough examination done from a gynecologist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
it can be just because he was too rough. sometimes if you are already close to your period the penetration can mimic the cramps that cause the period to occur in the first place and your body goes ahead with the period.