Ultrasound of my liver came back slightly abnormal?

I have a pain that comes and goes around my gallbladder area..it will hurt some..go away for a week or two and come back. I felt it was time i went to the doctor to get it checked out. He ran some blood work and said my blood came back ok. he did a xray and said that was ok. He told me it was more than likely a gallstone. He sent me to a place to get the ultrasound done..i called today for the results and they told me everything came back good..except of a slight abnormality with my liver..they said i should go to a Gastronurologist to look at it further..what does it mean slight abnormality?? could that make my area around my gallbladder hurt? Which type of doctor should I go to that can better help me?