My diarrhea went away for a week then came back?

i was fine till for a week even had some plums because i could not go, had a great bowel movemen, then had some chicken fron costco and bam the diarhea came back , so i went back to fluids blad foods could not go again had about 4 dried plums and bam the diarrhea came back last nite no fever no chills just a upset tummy, i am having Colonoscopy being done on thur, will this tell me whats wrong?