Gastroenteritis: This is often the most common cause of vomiting and fever, especially when the symptoms persist for more than a week. It can be caused by viral, bacterial, or parasitic infections.

Food Poisoning: Similar to gastroenteritis, food poisoning can cause prolonged vomiting and fever, especially if the causative agent is bacterial or parasitic.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can present with chronic gastrointestinal symptoms including vomiting and fever.
Appendicitis: Although appendicitis typically presents acutely, some cases can have a more prolonged course, especially if the appendix is partially obstructed or if the patient has a walled-off appendiceal abscess.

Meningitis: Although less common, meningitis can present with fever and vomiting, and it is crucial to diagnose promptly due to its high morbidity and mortality if left untreated.
Septicemia or Bacteremia: Systemic infections can cause fever and vomiting among other symptoms, and early diagnosis is critical for effective treatment.
Intussusception: A condition where a part of the intestine telescopes into another, which can cause intermittent vomiting and fever, and requires urgent medical attention.
Obstruction of the Intestine: Whether due to adhesions, hernias, or other causes, intestinal obstruction can lead to severe vomiting and fever, necessitating prompt surgical intervention.

Cyclic Vomiting Syndrome: A rare condition characterized by recurrent episodes of severe vomiting, which can be accompanied by fever.
Chronic Intestinal Pseudo-obstruction: A rare disorder of the intestinal muscles that can cause severe vomiting and fever due to the inability of the intestines to move food through the digestive system properly.
Neurological Disorders: Certain neurological conditions, such as brain tumors or Chiari malformation, can cause chronic vomiting and fever, although these are less common presentations.