Dear luinstran: Bloody discharge can result from infection, papilloma (a wart-like growth in the duct) and cancer, to name the most common sources. Even if the discharge resolves with the antibiotics, you might consider the appointment with the surgeon to be certain that there is nothing that requires further evaluation.
most things that cause bleeding from the nipple don't show on ultrasound or mammogram, so being ok doesn't really get you off the hook. Bloody discharge needs a definite explanation.