Talk to Psychiatry on Hairpin Shaped Stools

I have a trouble area a few inches above the navel on the left side. It feels constricted and pulsates all the time and swells up in response to many foods, which leads to fatigue, brain fog and depression. I have been on allergy & depression meds in the past. However, sometimes(a total of 5-6 times in the last few years) what has happened is that because of maintaining low stress and healthy diet for a long time, the swelling goes away, and fatigue etc literally vanish. And the first stool after swelling going away is always hairpin shaped, like a U whose two lines are touching each other. I am sure it holds the clue to the real cause of my issues and if dealt with, my symptoms will go away for good. Please tell the possible causes of hairpin stool and what should I do to investigate further. Many Thanks.