I Answered a question on yahoo answers about confusion of many females when they have a late period with blood or without appearance of blood, It may be a matter which involve many factors, as history of lateness of period or calculation of menstrual period next time, or may be a bacterial infection come with blood discharge.
I am a medical Lab Specialist:
Your case is frequent to me:
1-Negative Pregnancy test means that; NO pregnancy happened ever, if pregnancy test was POSITIVE with blood discharge, it may be a thing that might be interpreted as abortion/miscarriage.
2-Bloody discharge must be analyzed in a random urinalysis.
3-You are advised to consult a gynecology physician to maintain your menstrual period to be normal again.