Conclusion
While black stool may be a sign of internal bleeding, not all cases of black stool are caused by the presence of blood in the stool. Before worrying that you may have some type of internal bleeding, you should check what you ate. If your stool is often black even though nothing in your diet is responsible, you need to see a doctor.
References:
[1] https://www.medicalnewstoday.com/articles/325109
[2] https://www.medicalnewstoday.com/articles/325109
[3] https://www.buoyhealth.com/learn/black-stool#gastritis
[4] https://www.medicalnewstoday.com/articles/325109
[5] https://www.buoyhealth.com/learn/black-stool#gastritis
[6] https://www.medicalnewstoday.com/articles/325109
[7] https://www.cdc.gov/cancer/colorectal/statistics/index.htm