CBC (to rule out anemia)
BMP, LFTs
Lipase
Consider:
Acute abdominal series
?Barium swallow (upper GI series)
Endoscopy (most will be done as outpatient)
RUQ US
ECG/troponin
Acute abdominal series
?Barium swallow (upper GI series)
Endoscopy (most will be done as outpatient)
RUQ US
ECG/troponin
Gastritis
Gastroesophageal reflux disease 
Colitis
Peptic ulcer disease with or without perforation
Pharyngitis
Laryngitis
Pancreatitis
Conjunctivitis