This last week my 3 year old son has had a change in stool where it s become lighter (though still brown), thinner, and has mucus along with it. He also seems to be more tired than usual, taking longer naps, and still waking up with red under his eyes. He has not changed his diet, started any kind of school (he has gone to nursery on Sundays for a year and a half) or changed his behavior much that I ve noticed. Should I be worried, or should I assume that this is something that will pass?