My puppy sometimes do that. She has been wormed 4 times. She eats normal, play normal, but there is blood in her poo sometimes. She had her poop looked at by a vet, but found nothing. What's wrong?

What did the vet test for? There are a lot of different diseases that can cause bloody poop.

Is the poop solid? Or soft? Or water-like? Does it smell really, really bad?

Does she seem to want to eat a lot? As if she is never satisified with the amount given?