Tell him to try rinsing with semi flattened club soda. The effervescence of the club soda will break up the mucous, and help heal like the baking soda rinse. And I'll add what I always add - waterpik. Get one if you can he can use it on the lowest setting with the tongue cleaner head (blue one that looks like a spoon)it shoots water around the persons mouth to clean up all the gunk and if you add a little non alcoholic mouthwash it freshens too. tis awesome. So glad he finished. Hope he is doing ok.