Gastroesophageal Reflux Disease (GERD): This condition is common in the elderly and can cause epigastric pain, nausea, and decreased appetite due to acid reflux. The absence of bowel issues and the nature of the symptoms point towards an upper gastrointestinal issue.

Peptic Ulcer Disease: This includes both gastric and duodenal ulcers, which can cause epigastric pain, nausea, and decreased appetite. The pain can be related to eating and may improve or worsen with food intake.
Gastritis: Inflammation of the stomach lining can cause epigastric pain, nausea, and decreased appetite. It can be acute or chronic and has various causes, including infection, medication, and alcohol use.
Functional Dyspepsia: A condition characterized by recurring signs and symptoms of indigestion that have no obvious cause. Symptoms can include epigastric pain, nausea, and decreased appetite.

Myocardial Infarction: Although less common, myocardial infarction (heart attack) can present with epigastric pain, nausea, and decreased appetite, especially in women and the elderly. It is crucial to consider cardiac causes, especially if there are risk factors or associated symptoms like shortness of breath or chest pain.
Pancreatitis: Both acute and chronic pancreatitis can cause severe epigastric pain, nausea, and decreased appetite. The pain often radiates to the back and worsens after eating.
Gastric Cancer: Although less likely, gastric cancer can present with nonspecific symptoms like epigastric pain, nausea, and decreased appetite. It's essential to consider this diagnosis, especially in older adults with new-onset symptoms.

Zollinger-Ellison Syndrome: A rare disorder characterized by excessive gastric acid production due to a gastrin-secreting tumor, leading to severe peptic ulcers, diarrhea, and abdominal pain.
Eosinophilic Gastroenteritis: A rare condition characterized by eosinophilic infiltration of the gastrointestinal tract, which can cause abdominal pain, nausea, and vomiting, among other symptoms.
Infiltrative Diseases (e.g., Sarcoidosis, Amyloidosis): These rare conditions can affect the gastrointestinal tract and cause nonspecific symptoms like abdominal pain, nausea, and decreased appetite.