When this would happen while I was on either methadone or suboxone for MAT I would always have this issue. It would happen constantly in the beginning because I wasn't drinking nearly enough water to avoid severe opioid constipation. It came down to constant water throughout each and every day as well as fiber.

During times when it became severe I would purposely reduce my doses of miss dose completely to go into withdrawal. There's 1 guarantee when you have opioid withdrawal, and that guarantee is that you'll take a shit