<unk>  is a diagnosis of exclusion. Work-up should focus on ruling out more serious etiologies.
ECG
CBC
Chemistry
Troponin
CXR
Consider:
BNP
PT/PTT
D-dimer vs. CTA chest
ECG
CBC
Chemistry
Troponin
CXR
BNP
PT/PTT
D-dimer vs. CTA chest
Diagnosis of exclusion
Upper gastrointestinal endoscopy with<unk>  biopsies obtained to rule out other causes
Followed by<unk>  manometry
Esophageal spasm
Acute coronary syndromes 
Achalasia
STEMI
Esophageal injury
Non-STEMI
Subglottic stenosis
Unstable angina