Hi, I had gone through your question and understand your concerns. In your age some serious causes of postcoital bleeding are rare and most commonly this is related to injury during the intercourse so you should just avoid intercouse in next several days. Also, if there is vaginal discharge, fever or pain then it may indicate STD and you need to do std testing. Some other causes such as ovarian cysts, HPV infection or cervical mucosa changes are less common but should be considered if bleeding will be prolonged and in this case you should see gynecologist. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Wishing you good health.