Gastroenteritis: This is the most common cause of nausea and vomiting, often due to viral or bacterial infections, and can be accompanied by diarrhea and abdominal cramps. The duration of 5 days fits within the typical timeframe for a self-limiting gastrointestinal infection.

Food Poisoning: Similar to gastroenteritis, food poisoning can cause nausea and vomiting, usually within hours to days after consuming contaminated food. The symptoms can last for several days.
Viral Gastrointestinal Infection: Infections like norovirus can cause prolonged nausea and vomiting, often affecting multiple family members or individuals in close proximity.
Medication Side Effect: Many medications can cause nausea and vomiting as a side effect, and the onset can be within days of starting a new medication.
Pregnancy: Morning sickness is a common symptom in early pregnancy, characterized by nausea and vomiting, which can occur at any time of day.

Appendicitis: Although less common, appendicitis can present with nausea and vomiting, especially if the appendix is located near the stomach or intestine, causing irritation. Missing this diagnosis can lead to severe consequences, including perforation and peritonitis.
Intestinal Obstruction: This is a serious condition where the intestine is blocked, which can cause severe vomiting, abdominal pain, and constipation. Early diagnosis is crucial to prevent complications.
Pancreatitis: Inflammation of the pancreas can cause severe abdominal pain, nausea, and vomiting. It requires prompt medical attention to manage pain and prevent complications.
Kidney Stones: While primarily causing severe abdominal or flank pain, kidney stones can also induce nausea and vomiting, especially if the stone is obstructing the ureter.

Brain Tumors: Rarely, brain tumors, especially those in the posterior fossa or cerebellum, can cause persistent vomiting due to increased intracranial pressure or direct effects on the brainstem.
Addison's Disease: This is a rare endocrine disorder where the adrenal glands do not produce enough cortisol and aldosterone, leading to a variety of symptoms including nausea and vomiting.
Porphyrias: A group of rare genetic disorders that can cause acute episodes of nausea, vomiting, and abdominal pain, among other symptoms.
Cyclic Vomiting Syndrome: A rare condition characterized by recurrent episodes of severe vomiting lasting hours to days, with periods of normal health in between episodes.