The various causes for vaginal bleeding/spotting after sex are injury and friction, 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. Take care!