I would have a veterinarian take a look and diagnose, he may be developing a conjunctivitis which is highly contagious, wash your hands a lot.
It may be allergy related, food may have nothing to do with it.
In any event, if it is conjunctivitis it would respond to a prescription antibiotic ointment, left untreated, more serious problems could develop.
PS: The pruritus indicates an infection may be developing vs a simple discharge. Eventually the water discharge you describe could turn cloudy (pus) and a variety of colors.
