Achalasia: This condition is characterized by the inability of food to pass through the esophagus and into the stomach due to abnormal muscle contractions. Symptoms include dysphagia, chest pain, and regurgitation of food, which can be relieved by belching. The presentation of severe dysphagia and chest pain relieved only by belching strongly suggests achalasia.

Sliding Hiatal Hernia: This condition can cause symptoms of gastroesophageal reflux disease (GORD), dysphagia, and chest pain, which may be relieved by belching. The herniation of the stomach into the thorax can lead to these symptoms due to mechanical obstruction and reflux.
Gastric Volvulus: Although less common, gastric volvulus can present with sudden onset of severe dysphagia and chest pain, which may be relieved by belching if the volvulus is intermittent. However, a volvulus of more than 180 degrees can lead to gastric strangulation, which is a medical emergency.

Gastric Strangulation (complication of Gastric Volvulus): This is a life-threatening condition that requires immediate surgical intervention. Any suspicion of gastric volvulus with significant symptoms should prompt urgent evaluation to rule out strangulation.
Esophageal Stricture: While not typically relieved by belching, esophageal stricture can cause dysphagia and chest pain. It's crucial to consider this diagnosis, especially if there's a history of chronic GORD or caustic ingestion.

Barrett’s Esophagus: While Barrett's esophagus is a complication of long-standing GORD, it typically does not cause dysphagia or chest pain relieved by belching. It's more associated with an increased risk of esophageal adenocarcinoma.
Other Motility Disorders: Conditions like diffuse esophageal spasm or nutcracker esophagus can cause chest pain and dysphagia but are less likely to be relieved specifically by belching compared to achalasia.