Eat low fiber foods so your gut has less work to do. Instead of high amounts of cooked veggies turn half of them into juice which has much less fiber. Avocado has fiber so less of that even though it has good oil.
Meat has always agreed with my colon, easy to break down.
When my gut acts up I always go to: chicken broth, chicken, well cooked baby carrots, cooked spinach.
Dessert: cooked apple or applesauce.
Drink lots of water (not caffeinated beverages) and a spoonful of coconut oil can be put in a smoothie for extra credit
Good luck with everything including the c-scope. The prep is yuck but must be done.