Help! My puppy is pooping blood! Could it be something she ate? Or is there something really wrong with her? She's still eating her food.

If she has blood in the stool, there really is something wrong with her. I am not sure it is helpful to speculate what it could be. She needs to get to the vet today if at all possible.

Yes, it could be several things but there is no sense speculating what it could be. The dog needs to go to the vet asap.