Since you went offline, I am answering your question. A hard stool can be felt through the vaginal wall, as rectum and vagina are adjacent organs and have a just thin wall in between them. So if you have habitual constipation, your stools are frequently hard and you need to strain during passing motion, stool can be felt through the vagina. Internal hemorrhoids too can be felt through the vaginal wall, if they are big. A rectal polyp, also can be felt through the vaginal wall. An abdominal pain, lower back pain will need evaluation by an ultrasound, barium enema, especially if there is a history of passing blood in stool. Hemorrhoids, polyp, rectal mass, inflammatory bowel disease needs to be ruled out with your symptoms, by following investigations;
1) Anoscopy; anal examination; can be done in office
2) Proctoscopy; rectum examination; office procedure.
3) Flexible sigmoidoscopy and colonoscopy; examination of sigmoid colon and whole of the colon by a camera.
These would clinch the diagnosis.
Please feel free for your follow up questions.