You are having blood and blood clots
as per vagina, after having sex after a long time , which might be due to tear in your vaginal or vulvae wall , also having pain and burning , than try to wash with cold
antiseptic liquid immediately , if bleeding still persists , than you must contact and take advise of your gynecologist near by you. don't ignore it otherwise some infection or complication may be there. Good Luck and take care.