What Causes C-diff With Severe Diarrhea Plus Edema?

If you have c-diff with severe diarrhea, yet extreme edema in the lower extremities, what kind of diuretic could you take to relieve some of the fluid and not dehydrate? The edema is not from CHF and is not normal for this person. She is s/p bowel surgery and was recently on TPN for 4 weeks prior to surgery. What will help?