Chronic Pancreatitis: This is a plausible diagnosis given the question's context, as chronic pancreatitis can cause recurrent or persistent abdominal pain, often radiating to the back, and is associated with pancreatic inflammation and fibrosis.

Peptic Ulcer Disease: Conditions like gastric or duodenal ulcers can cause chronic abdominal pain and are common enough to be considered in the differential diagnosis.
Inflammatory Bowel Disease (IBD): Crohn's disease and ulcerative colitis can present with chronic abdominal pain, changes in bowel habits, and other systemic symptoms.
Irritable Bowel Syndrome (IBS): Although IBS is more functional in nature, it can cause significant chronic abdominal pain and alterations in bowel habits, making it a consideration.

Pancreatic Cancer: Although less common, pancreatic cancer can present with chronic abdominal pain, weight loss, and jaundice, making it a critical diagnosis not to miss due to its poor prognosis if not caught early.
Gastrointestinal Obstruction: Conditions causing bowel obstruction can lead to severe, chronic abdominal pain and are medical emergencies.
Mesenteric Ischemia: This condition, involving insufficient blood flow to the intestines, can cause chronic abdominal pain and is potentially life-threatening if not promptly addressed.

Eosinophilic Gastroenteritis: A rare condition characterized by eosinophilic infiltration of the gastrointestinal tract, leading to chronic abdominal pain, among other symptoms.
Celiac Disease: An autoimmune reaction to gluten, leading to small intestine inflammation and chronic abdominal pain, although it's more commonly associated with malabsorption symptoms.
Abdominal Migraine: A rare condition in adults, more commonly seen in children, characterized by recurrent episodes of severe abdominal pain, often accompanied by other migraine symptoms.