pancreatitis

This is a late reply and not likely to be useful now.

I would say it can be pancreatitis. My children had many bouts of pancreatitis starting when they were very young and the blood work was always fine. Then sometimes starting at age 10 or so the lipase and amylase levels were high when they had a bout, but not always. Once their pancreases were sufficiently ravaged the blood levels showed normal during bouts. This always confounded new doctors. My kids never had back pain in there teen years but did as young adults and as adults. It's surprising how many doctors have never heard of chronic and hereditary pancreatitis. Also, they think, if you don't match every symptom, you must have something else.
Pain, vomiting, diarrhea and a CT Scan showing an inflamed pancreas and you'd better consider that it just might be pancreatitis.

My definitions:
Acute - Hurts like hell right now.
Chronic - Had it all my life.
Hereditary - Runs in the family.

Hope this helps some poor soul with backward doctors.
Lord Help Us!
SP