Gastroesophageal Reflux Disease (GERD): This condition is characterized by stomach acid flowing back into the esophagus, causing pain and discomfort, especially after lying down or upon waking. The symptoms can be exacerbated by eating close to bedtime, which makes it a common cause of morning stomach pain.

Peptic Ulcer Disease: Stomach ulcers or duodenal ulcers can cause pain that may worsen at night and upon waking, especially if the ulcer is located in a position that allows acid to come into contact with it more readily when lying down.
Gastritis: Inflammation of the stomach lining can lead to pain and discomfort, which may be more noticeable in the morning due to increased acid production.
Irritable Bowel Syndrome (IBS): Although IBS can cause a variety of symptoms, including abdominal pain, it might not typically follow a pattern of worsening upon waking. However, some individuals may experience morning exacerbations.

Myocardial Infarction (MI) or Cardiac Ischemia: Although less common, chest pain or discomfort that radiates to the abdomen can be mistaken for stomach pain. It's crucial to consider cardiac causes, especially in individuals with risk factors for heart disease.
Pulmonary Embolism: Severe, sudden-onset chest pain that might be referred to the abdomen, accompanied by shortness of breath, could indicate a pulmonary embolism, which is a medical emergency.
Appendicitis: While appendicitis typically presents with pain that initially is diffuse or around the navel and then localizes to the lower right abdomen, atypical presentations can occur, and missing this diagnosis can have serious consequences.

Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic abdominal pain, which might be worse in the morning due to bowel habits or increased inflammation during the night.
Gastric Cancer: Although rare, especially in younger populations, gastric cancer can cause persistent abdominal pain, among other symptoms like weight loss and difficulty swallowing.
Pancreatitis: Inflammation of the pancreas can cause severe abdominal pain that radiates to the back, which might be constant or worsen after eating, including in the morning after an overnight fast.