Doctor called, low b-12, low iron and low vitamin d. how can this happen?! this is upsetting.

Deficiency: These deficiencies can and should be treated. Low iron occurs from blood loss, most likely from menstrual bleeding. B12 deficiency can lead to pernicious anemia with neurological deficits and requires injection therapy. A Schilling test can be done to document that you are unable to absorb B12 by mouth due to lack of stomach acidity. Discuss with your physician.