I hate hearing that he's having so much trouble. It would be concerning to still have nighttime accidents after 10 mos. What does your surgeon say? Our daughter struggled for a month or two with that, about as long as her surgeon said it would. If they used the double-staple technique it can really stretch their bottoms and it takes time for the muscles to strengthen back up.
Of course, with the constant pressure it may be something else - cuffitis maybe? Any other symptoms?
Steve