What Causes Back Issues With Normal Abdominal Ultrasound?

My doctor sends you for tests at the drop of a hat. I had an abdobinal ultrasound (with a lower spinal MRI) about 4 months ago becasue I was having back issues and everything was normal. I just started taking (1 month) Dutoprol 25/12.5. He took a blood test and the AST was 36 and the ALT was 69 and he wants me to go for another ultrasound. What is your thought?