
Hi,
Earmites do feed on inner ears. This could be what is causing the blood, perhaps that, along with her scratching, has caused fresh blood. In the past I've also had this problem.
The vet will be the best one to advise you. I manage my dogs ears myself now, my breed have large flappy, very hairy ears and I usually clean them once a week with a saline solution and Thornit, if necessary.