Golden Labrador behaving?

Been on here again tonight asking for advice about my new puppy, she is 9 weeks old and been checked over by a vet who said she is fine. She was on Kibble when i bought her and changed her from that to Dried food Science Plan and ever since she had had an upset tummy 4 times a day and it looks now like there is some blood in it..now i feel panic...i know when a human has the runs for a few days they get blood in there poo but is it the same for a dog. I am going to ring vets tomorrow to make an appointment. But if anyone else has had this problem please let me know and advise, thankyou