I would not want you to remove dairy from his diet long term because he needs the calcium but you could try and
remove all foods that have dairy for a few days just for a test and
see if that goes away. Mine started with mucus in
the <span style = 'background-color: #dae8f4'>stool</span>
. Then around 11yrs it turned in
to diarrhea and
stomach pain. Generally mucus is from irritation. Keep a food diary of everything he is eating so you can track it and
see if it is something else he is eating.