I fear you misread my post. I wrote that I developed C-diff from the ANTIBIOTICS my dentist gave me (not vitamins). They used to give out antibiotics like candy. I was a text book case - I developed terrible diarrhea on the 10th day of antibiotics (Amoxicillin, known cause) and was so weak I couldn't drive. My Primary sent me to emergency room and the blood work showed a very low potassium level (they said my heart could have stopped) and put me in hospital. The low potassium was obviously caused by the dehydration with such heavy diarrhea. Blood work in the following years after have shown I have low potassium so my Primary prescribes it now. I am not relating potassium to C-diff except with diarrhea/dehydration one loses electrolytes (sodium, potassium calcium, magnesium, phosphate, and chlorine.)

Regarding how one develops C-Diff, while hospitals and nursing homes are common places (patients on antibiotics) , anyone can develop C-diff if they are on certain antibiotics. Broad-spectrum antibiotics are a risk for C-diff because they kill the good bacteria and the bad bacteria take over. Then if there is not strict hygene others can pick up the bacteria from contaminated surfaces.
Example: When I was in the hospital in Naples, Florida, outside my room there was a stand with gowns and gloves for anyone coming into my room. The staff rarely put on any protective clothing. Only if the head of the hospital was coming by. In fact one employee came into my room and said she was pretty healthy and not worried about C-diff - she missed the point. She could carry the germ to others!
But having a contagious disease did get me a private room at the time!
https://www.mayoclinic.org/diseases-conditions/c-difficile/symptoms-causes/syc-20351691