My 15 yr old son was diagnosed last year with IBS.
He had hidden the fact that he had soiled himself on a few occasions. But last year on a 2 day hike with the scouts he dropped out. His leader wasn't happy with him thought he was swinging the lead. Brought him home son in tears. We cleaned him up and then found out he'd soiled himself again. He then admitted he'd been doing it for some time etc, and sometimes couldn't even go to the toilet.
Husband took him to the Drs who sent him for blood tests etc it was diagnosed IBS stage 3 bordering chrons. He's now on medication. His scout leader apologised all his scouting and school friends now know and support him he has a toilet card for school I case he needs to go.
He can go for days without problems then he'll have back ache and stomach cramp and be constipated, he goes to the gym regular but this seems to irritate, him.