Thank you for the prompt reply.
From the symptoms that you describe, I would be most suspicious of inflammatory bowel disease (IBD) but pancreatitis certainly has to be on the list of rule outs. Both can be very challenging to confirm without more advanced diagnostics (besides blood work) and ultimately, in most cases, the only definitive diagnosis, requires biopsy of the affected tissue. The good news is that the treatment for IBD is often symptomatic in the early stages and often, even when more therapy is needed, therapeutic trials to treat IBD or the commonly encountered intestinal cancer are offered.
If additional testing such as xray or ultrasound of the abdomen has not been offered, I would start there. If nothing abnormal is noted (which is common), I would talk with your vet about treatment for intestinal infiltrative diseases, such as IBD or small cell lymphoma, and use response to therapy to help confirm the diagnosis.
I hope this is helpful. Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please reply so I can clarify for you.
My posted replies are for general education only and not meant as a diagnosis. Only after a thorough veterinary examination can a diagnosis for your pet be made and specific treatments be advised or medications be prescribed.