What Causes Bleeding After Passing Stools?

For past 3 days after I eat my dinner meal I have I dyer need to go to rest room. I have diarrhea really bad my stools are almost watery. Tonight after I went I wiped a lot of blood. I having changed anything in my routine or my food, no Medicie or laxatives. Could I have some type of disease or is the blood just I eternal hemorrhoids?