Blood cloths wouldn’t affect a single tooth and most likely affect an entire area or quadrant. Once a tooth loses its blood supply it turns dark and requires root canal therapy to remove the necrotic tissue however the tooth still remains within the periodontal sucket and will survive for years to come. Sudden loss of a tooth the way she describes it would be caused by a rapid acute event causing bone loss around the affected tooth. That is accompanied with pain and inflammation. It would be easier to determine the cause with radiographs. I will look more into this and share any findings with the board. Have a wonderful thanksgiving everyone.