HI I have gone through your mail and as you said that your 4 year old daughter complaining of blood in her ear without any pain and you saw black stuff in the ear,your this observation put me to think about associated otitis externa
or there is also possibility that wax of ear may create some discomfort in ear and she had hurt her ear by her nails in itching.though it is not an emergency but one should rule out diseases leading painless ear bleeding like- Thrombocytopenia
, sickle cell anaemia
and lastly leukemia
. So you should contact E.N.T.specialist and Pediatrics, for examination and to find out the real pathology.