Hello and welcome to HCM, Abnormal vaginal bleeding after performing sex needs to be investigated first. Post-coital bleeding as it is called occurs due to infection or inflammation of the endometrium, cervix or the vagina. Cervical erosion is also a cause of post-coital bleeding. More serious conditions like carcinoma of the cervix can also cause post-coital bleeding. Thus, a clinical assessment by your gynecologist is required to examine the cervix and rest of the genital tract. The bump which your partner has felt also needs to be examined. Since, you were unaware of the bump, it seems that the bump was painless. However, a clinical assessment will be required to find out the character of the lesion and hence plan its management. Thanks and take care Dr Shailja Puri