I Had A Right Side Colectomy 20 Months Ago Due

I had a right side colectomy 20 months ago due to appendix removal and then sepsis. Now my bowel movements are running and black tar and green poop and then yellow poop and I get 20 seconds notice when i have to go. A doctor said my valve was taken out during the surgery. He wants to do an upper endoscopy this week, my question is why do that if he knows already its gone and in hs wrds I'm an open spiket so to speak