Gastroesophageal reflux disease (GERD): This condition can cause both diarrhea (due to malabsorption or increased gut motility) and hiccups (from irritation of the diaphragm by stomach acid). The chronic nature of the symptoms fits with a long-standing condition like GERD.

Irritable Bowel Syndrome (IBS): IBS can cause chronic diarrhea and, although less commonly, hiccups might occur due to the abdominal discomfort or gas associated with IBS.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can lead to chronic diarrhea. Hiccups could be a less common symptom, possibly related to the inflammation affecting the diaphragm or due to medications used to treat IBD.
Gastroparesis: This condition involves delayed stomach emptying, which can lead to diarrhea and potentially hiccups if the delayed emptying causes gastric distension that irritates the diaphragm.

Cancer (e.g., stomach, pancreatic, or lung cancer): Although less likely, certain cancers can cause both chronic diarrhea (through various mechanisms like malabsorption, hormone production, or direct intestinal involvement) and hiccups (especially if the cancer involves or compresses the nerves controlling the diaphragm).
Infections (e.g., giardiasis, amoebiasis): Chronic infections can cause prolonged diarrhea. While hiccups are less common, severe infections could potentially irritate the diaphragm or cause systemic symptoms that might include hiccups.
Medication side effects: Certain medications can cause both diarrhea and hiccups as side effects. It's crucial to review the patient's medication list, especially for recent additions.

Eosinophilic gastroenteritis: A rare condition characterized by eosinophilic infiltration of the gastrointestinal tract, which can cause chronic diarrhea. Hiccups could potentially occur due to the involvement of the stomach or the presence of eosinophils affecting the diaphragm.
Diabetic gastroparesis: Although more commonly associated with nausea and vomiting, diabetic gastroparesis can lead to diarrhea in some cases. The delayed gastric emptying might also cause hiccups due to gastric distension.
Sjögren's syndrome: An autoimmune disorder that can affect the gastrointestinal system and cause diarrhea. While less common, it might also lead to hiccups through mechanisms similar to those in other autoimmune diseases affecting the nerves or muscles.