Thanks for writing, Id.
Yes; it is common to have loose stools after a SBFT (small bowel follow through), especially if you are already having small bowel "issues." People who are already inflamed may find the contrast material--or any substance, even food--irritating, and excessively stimulating to the bowels.
About your lab tests: the MCH (mean corpuscular hemoglobin) value is the amount of hemoglobin in an average red blood cell. A high MCH suggests a type of anemia known as macrocytic anemia; lack of folic acid and/or vitamin B12 is often a cause of this type of anemia.
The vitamin deficiencies (vitamins B12 and D) and the electrolyte deficiency (the low level of the mineral, calcium) you describe are often seen in small bowel disease, such as seen in Crohn's disease, celiac disease, or in some other malabsorption problems related to small bowel disease.
As for the low white blood cell count (WBC), it would help to know if you are taking any drugs that might be causing a lower than usual value.
Good luck with your upcoming colonoscopy.
My best,
Hope
You certainly are having your share of