Brief Answer:
Consult a Gynecologist at the earliest
Detailed Answer:
Hi there,
Thanks for your query.
Bleeding during intercourse occurs due to :-
*    
Injury of the vaginal wall due to tears following any cause, including vigorous intercourse.
*    An infection (parasitic or yeast), causing inflamed vaginal wall, which bleeds due to friction
*    Cervical erosions (soreness of uterine opening)
*    Small growths (non-cancerous) inside the 
uterus or arising from the inner lining of the uterus.
*    Thinning and dryness of vaginal wall following 
menopause. This condition- called Atrophic Vaginitis- is caused by reduced secretions which keep the vaginal wall lubricated.
*    In some cases, bleeding may point towards the possibility of cancer of 
cervix or vagina.
Therefore, consult your gynecologist at the earliest, who will examine you, take a 
PAP smear, establish the exact cause of your problem and advise you the best course of action available.
Hope I have addressed to your concerns to your complete satisfaction and you find my response helpful and informative. I will be happy to answer further queries, if any.
Fond regards and have a nice day,
Dr. Rakesh Karanwal