I'm a Pediatric RN and the youngest that I have heard of was a 3 y.o. There is a huge increase in Pediatric Chrohns cases.We are watching my 8 y.o also,he has stomach issues sometimes,cramping.... keeping my fingers crossed. BUT,there are quite a few reasons why kids can have blood in their diaper,food intolerances,viruses,hard stools...so try to stay positive,although I know it can be worrisome,always a Mom's job to worry