What Causes Intermittent Pain In Abdomen Along With Vomiting?

I have had pain in the upper abdomen with vomiting on and off for over two months. When I was first tested I had slightly increased lipase levels. Since then I have had over 10 blood tests, which have shown increased bilirubin and GGT and lower than normal lipase. I have tested negative for Hepatitis. I have had a CT scan and two ultrasounds and my liver, biliary duct and pancreas all look normal. What could be going on? I am being tested for parasites this week. Are parasites a possible cause or something else?