Had the scan done and they checked abdomen, gallbladder, liver and kidneys. They didn't find anything wrong with any organs so I'm still no closer to any answers about what the pain is but it's a relief that all my organs are okay. I think it must be rib inflammation like the first doctor said but I don't know how they can check for that.
The only thing she did say is that I have a liver hemangioma which is a harmless birthmark on the liver. She said it will always have been there. I've read that pregnancy could have made it worse because of the extra estrogen. It is their protocol to follow up on the hemangioma as this was my first scan of this type so I have to go back in a few months for another scan.