Viral Gastroenteritis: This is a common condition that often starts with non-specific symptoms like giddiness or dizziness due to dehydration or viral effects, followed by abdominal discomfort, nausea, vomiting, and diarrhea. The sequence of symptoms can vary but often includes gastrointestinal upset after initial systemic symptoms.

Food Poisoning: Similar to viral gastroenteritis, food poisoning can cause initial systemic symptoms like giddiness due to toxins affecting the body, followed by abdominal cramps, diarrhea, and vomiting.
Gastroesophageal Reflux Disease (GERD): While primarily known for causing heartburn, GERD can lead to abdominal discomfort. If a patient experiences significant discomfort or anxiety from GERD symptoms, it might precipitate feelings of giddiness.
Irritable Bowel Syndrome (IBS): IBS can cause a variety of abdominal symptoms, including discomfort. Stress and anxiety, which can be associated with IBS, might also contribute to feelings of giddiness.

Appendicitis: Although abdominal pain typically precedes systemic symptoms in appendicitis, it's crucial not to miss this diagnosis. Early appendicitis might present with non-specific symptoms, including giddiness due to pain or anxiety, followed by more localized abdominal pain.
Myocardial Infarction or Cardiac Issues: In some cases, especially in older adults, cardiac issues can present with atypical symptoms, including abdominal discomfort and giddiness due to decreased cardiac output or arrhythmias.
Pulmonary Embolism: This is another critical diagnosis not to miss. While it typically presents with respiratory symptoms, some patients might experience giddiness due to hypoxia or decreased cardiac output, accompanied by abdominal discomfort if the embolism affects bowel perfusion.

Porphyrias: These are a group of rare disorders that can cause a wide range of symptoms, including abdominal pain, neurological symptoms, and psychiatric disturbances. Giddiness could be part of the neurological presentation.
Addisonian Crisis: A life-threatening condition due to adrenal insufficiency, which can present with non-specific symptoms including giddiness, abdominal pain, and vomiting.
Neurological Conditions (e.g., Migraine, Vestibular Disorders): Certain neurological conditions can cause giddiness as a primary symptom, with abdominal discomfort being secondary, possibly due to associated nausea or stress response.