Has anyone ever had a light ran to their stomach before?

I have been having some stomach/chest pains. I went to the doctor and they sent me for a sonogram of my gallbladder and my liver. I was supposed to find out the results today, but I missed my appointment. The doctor called me and set me up another appointment and said she wanted to talk to me about running a light down my stomach. Now my appointment is 3 days away and I'm really nervious, Why would they want to do the light thing? Do you think that my sonogram came back good and she wants to explore other possibilities? What do they check for when they do that? I'm going crazy thinking about this!!