It sounds like you are experiencing a case of vaginal prolapse.
It is a condition that can develop after giving a childbirth, as a result of weakened muscles, ligaments, and skin in and around a vagina.
These structures keep the womb, rectum, bladder, urethra, small bowel, or the vagina itself at the right place, and when they are weakened or broken some of these organs can begin to prolapse, or fall, out of their normal position.
Without medical treatment or surgery, these structures may eventually prolapse farther and farther into the vagina or even through the vaginal opening.
Long, difficult labors and large babies are especially stressful to these structures. Childbirth is the risk factor most commonly associated with rectocele (prolapse of the rectum through the vaginal wall).
Visit your gynecologist!