congestive heart failure , cholestasis (congestion of the bile ducts) , cirrhosis, hepatitis ,
liver ischemia (blood flow deficiency),
liver necrosis,
liver tumor, high
alcohol intake, use of hepatotoxic drugs (drugs toxic to liver).
So, since the ALT rise is higher than that of AST and GGT is high, the cause is probably in liver. Since liver is enlarged and you have acid reflux and diarrhea, bile duct obstruction and cirrhosis (does ultrasound mention this?) will have to be ruled out.