I would imagine he may have ulcers more so then colic, he was living in a stressful situation, traveling can be stressful, new environment ect. If a horse is a worrier then ulcers are likely, and the pain can mimic a colic.
My Paso Fino gelding is a worrier always has been and used to get terrible tummy aches when I would ride him alone and acted colicky, I would give him some banamine and then he was fine. Then he got chronic diarrhea, and it smelled just awful. I had the vet did a cbc and everything was fine so the vet guessed ulcers. He gave me gastrex to give him for two weeks it coated his stomach and gave him relief from the pain. He also recommended feeding him alfalfa which is also good for their gut. I also feed beet pulp and no grain. After about two days his stools got better he was eating better and just acted better. So now before I ride him in a show or long trail ride or anything stressful I give him some gastrex and a some alfalfa cubes, with beet pulp. Keeping food in the gut helps keeps stomach acid from sloshing around and causing pain, and since the cubes and beet pulp are soaked in water it gets some extra water in them.
Maybe you could just take him to a local show and just ride around without entering any classes, that way you can kind of gauge his reaction. If he gets to stressed you can do some work to calm him, but not invest in entering a class, and you can always take him home. You will never know unless you try.