I am passing very little blood from my vagina over 3 days now. i don't have any pain .sometime the blood is dark color . what can cause that bleeding ?

Are you pregnant?: You need to check if you are pregnant. There are wide range of causes of your symptoms otherwise, and I suggest to see your doctor if it continues past a week for further assessment and management

Bleeding: First of all, are you still menstruating? Age? Abnormal bleeding does not have to mean anything bad, but if you are postmenopausal- see M.D. If you are or could be pregnant, see M.D. If this persists or you continue to have irregular periods l, also see M.D.