Gallbladder Disease (Cholecystitis or Cholelithiasis): This is the most likely diagnosis due to the location of the pain (right epigastric) and its relation to eating, which can trigger gallbladder contraction and exacerbate symptoms if stones or inflammation are present.

Peptic Ulcer Disease: Ulcers in the stomach or duodenum can cause epigastric pain that may radiate to the right side and is often exacerbated by eating.
Gastroesophageal Reflux Disease (GERD): While GERD typically causes heartburn, it can also lead to epigastric pain, especially after eating.
Pancreatitis: Inflammation of the pancreas can cause severe epigastric pain that may radiate to the back and is often worsened by eating, especially fatty foods.

Myocardial Infarction: Although less common, myocardial infarction can present with epigastric pain, especially in women, and is a critical diagnosis not to miss due to its high mortality rate if untreated.
Pulmonary Embolism: In rare cases, pulmonary embolism can cause referred pain to the epigastric region, especially if the embolism involves the lung bases.
Aortic Dissection: This is a life-threatening condition that can sometimes present with epigastric pain if the dissection involves the descending aorta.

Hepatic Abscess or Cyst: Infections or cysts in the liver can cause right upper quadrant or epigastric pain, especially if they are large or become infected.
Right Lower Lobe Pneumonia: In some cases, pneumonia affecting the right lower lobe of the lung can cause referred pain to the epigastric region.
Intestinal Obstruction: Although more commonly associated with abdominal distension and vomiting, intestinal obstruction can sometimes present with epigastric pain, especially if the obstruction is partial or involves the proximal small intestine.