What Causes Blood In Stools In Children?

hello my six year old boy went to toilet and when i cleaned hime there appeared to be some blood on tissue, looked closely because yesterday he was eating strawberries but it does look like blood. I could see any in toilet or son his stools. He is not constipated as he goes to toilet everday.I have noticed this about twive before and can t remeber the period betwwen these previous times.