Viral Gastroenteritis: This condition, often referred to as the stomach flu, is characterized by nausea, vomiting, diarrhea, and can sometimes include throat tightness if the virus affects the throat. It's highly contagious and common, making it a likely diagnosis for these symptoms.

Food Poisoning: Similar to viral gastroenteritis, food poisoning can cause nausea, vomiting, and diarrhea. Throat tightness could be due to an allergic reaction or irritation from the ingested substance.
Allergic Reaction: An allergic reaction could explain the throat tightness and potentially the gastrointestinal symptoms if the allergen was ingested.
Influenza: While primarily known for respiratory symptoms, influenza can also cause gastrointestinal symptoms like nausea, vomiting, and diarrhea, especially in children.

Epiglottitis: A severe and potentially life-threatening condition where the epiglottis becomes inflamed, which can cause throat tightness and difficulty swallowing. It's less common but critical to diagnose early.
Anaphylaxis: A severe, life-threatening allergic reaction that can cause throat tightness, nausea, vomiting, and diarrhea among other symptoms. Immediate medical attention is required.
Botulism: A rare but serious illness caused by a toxin that can lead to nausea, vomiting, diarrhea, and difficulty swallowing due to muscle weakness.

Eosinophilic Esophagitis: A chronic immune system disease in which a type of white blood cell, the eosinophil, builds up in the esophagus in response to an allergen or irritant, leading to swallowing difficulties and potentially throat tightness.
Ciguatera Fish Poisoning: A rare condition caused by eating fish contaminated with ciguatoxins, which can lead to gastrointestinal and neurological symptoms, including throat tightness.
Scombroid Poisoning: Caused by eating spoiled fish that contain high levels of histamine, leading to symptoms that can include throat tightness, nausea, vomiting, and diarrhea.