My 11 week old KC Cavalier has some bleeding from his rectum?

He had his glands cleaned at the vets as he had been scooting. He had a little diarrhea for a couple of days which I put down to the hunger strike he had been on. I have just watched him have a movement and went to clean it up when I noticed red blood on the gr (a little) I have checked his bum and he has some in his fur. I don't believe it is internal but that he has been irritated by the vet. He is happy, eating well and drinking plenty. has anyone experienced anything similar??