Hello, I can understand your problem. Having blood in stool just before a week of your menstruation suggests that you might have endometriosis. Endometriosis is a condition where entometrium (lining of uterus) is found outside the uterus. It can be present in lining of abdomen or in the bowel, too. It may be possible that the uterus lining that should shed off during menstrual bleeding does not shed off completely and gets embedded in the bowel causing bleeding. However, you need to visit a gynecologist for physical examination. As endometriosis can be diagnosed precisely by surgical examination only called laparoscopy, the gynecologist may prefer to try hormonal medications and painkillers before any surgical intervention. You may have to go for Ultrasonography to rule out presence of cysts in ovaries due to endometriosis. I would advise you not to worry about this condition as it is very common among females and manageable. I hope this information helps you. Thank you for choosing HealthcareMagic for advise. Take care. Best, Dr. Viraj Shah