You had a lot of colon removed. My surgeon said it can take a long time for body to adjust, especially if part of rectum was removed. Because of my shortened colon and rectum, I have to have a bowel movement at least 8 times during the day and usually I wake up during the night and have to go. I feel pressure often and must go to toilet. Doctor said this should improve, but no guarantee. I do not have diarrhea like you, just extremely high frequency.
F 9/14/17 blood, 10/05/17 endoscopy/colonoscopy 4.5 cm tumor lower colon/upper rectum/left side -11/09/17 open Rectosigmoid Colon Resection remove invasive adenocarcinoma, moderately diff marg clear.15 lymph nodes neg malignancy. benign liver w/fibrous nodule- rectum at 15cm Tumor location: above peritoneal reflection 4.2 x 2.7 cm Tumor inv muscularis closest 1.5 cm. pT2pNO Stage 1. No Lynch