Vets, we’re stumped. Did the liver or pancreas cause this first?

My 6-year-old, 11.5-pound dog suddenly developed bloody diarrhea and vomiting and couldn’t keep water down. Her ALT was 1,311, with elevated ALP and GGT. The ultrasound showed inflammation in her pancreas and GI tract, but her pancreatic lipase was normal.
She’s hospitalized and improving with IV fluids and medication, but the doctors don’t know whether the liver or pancreas was affected first. It’s basically a chicken-or-the-egg situation.
Has anyone seen this combination before? What could cause it?