sick dog? looking for input

mr. met

i leave my 10.5 month-old puppy in her crate every weekday when i go to work. three times in the past month and a half ive come home to a crate full of diarrhea. upon taking her out, she usually as a bit more to expel, and at the end there is usually a little bit of blood. she acts completely normal (eating, drinking, running, playing) and is totally fine for the rest of the night and the next day. should i be worried or should i just assume that she ate something that she shouldnt have or maybe just has a sensitive stomach? any input is appreciated.