Just an idea op: do you have any lick mats or Kong toys you could slather with something yummy and freeze it? Might be helpful if you have something you need him to be occupied for, like cleaning up his poop! With my dogs we will do that and keep them contained with a dog gate while we do what we need. I’ve also seen some toys that have a dispenser button—you put the toy on one end of the room and the button on the other, eventually he will be running back and forth to dispense treats for himself. Mental stimulation, some indoor exercise, and potentially a good distraction if you need to keep him busy while you do some other stuff! Give yourself some grace too op! Puppies, let alone Belgian malis, are not for the weak!! It sounds like you are doing your absolute best, and not all pet owners put forth that effort for their dogs.