My 75 year old sister..very vibrant..on no meds except thyroid low dose..has developed sudden onset of chronic diarrhea.. We know the exact date..Feb. 15th a day after a her anniversary celebration at at restaurant ..she has had fecal tests done..no concerns reported..blood work checks out normal..no pain or fever..is up all night ..reports 9 episodes just in one recent night. Observed blood in stool the night before colonoscopy..that was today..no polyps.. Biopsy of Colon lining taken..3 months of diarrhea.. Even on extended periods of brat diet..where do we go next. Our family wants to be very pro active and not miss a clue. What tests should we be asking for next? The blood in her stool was dark..upper GI?? Thank you so much!