Thank you for your query.
Just to be sure that I have understood your problem properly, you mean your son is passing some discharge from his anus. If this is the case then is he constipated because at times severe constipation
can present with some liquid passing through the sides of the constipated stool. In this scenario I would advise that you consult your doctor who may confirm it and advise you to take steps to control constipation.
If he is constipated then medications will be a temporary relief. Nutritional adjustment would be the best course. I suggest you visit http://www.vardaan.net/hl-chfd.php where you will find some useful instructions on high fibre diet.
I hope I have answered your query to your satisfaction.