Liver question... Should I be worried?

I went in for a physical August 10, and since then I have been back to the doctor 3 times for followup bloodwork because it turns out I have high conjugated bilirubin levels. I feel completely fine, and tests for mono and hepatitis came back negative. I do not have Gilbert's Syndrome, as they originally thought. However, I am getting a liver ultrasound tomorrow and was wondering what they are looking for and what could possibly be wrong with me?