Basia has EPI. If Ronin actually has this, you need to put him on digestive enzymes (I get my enzymes shipped to me from Canada, actually). Did you do the blood test? It checks for TLI (Trypsin Like Immunoreactivigy).
Check this out: http://vetmed.tamu.edu/gilab/service/assays/tli
If there are any aspects that you don't understand about the disease, I can try to help explain.
ETA: if you haven't done the blood test- but you plan to: make sure to also test for Folate and Cobalamin (vit. B12)