What GI issues need to be diagnosed/treated early lest they cause permanent damage or become unrecoverable. An example would colon cancer.
The question is about which possible diagnoses need to be crossed off the list before it is reasonable to take an alternative approach.
For example if colon cancer is a possible diagnosis, one would want testing asap to, hopefully, rule it out.
If CC were the only serious possible diagnosis, then after ruling it out priorities qualitatively change. It becomes reasonable switch to a less aggressive approach, such as the other extreme of simply giving the body time to heal itself.
Could waterborne infections, including Giardia and Criptosporidium, microscopic colitis and bile malabsorption result in permanent damage?