Vasovagal Syncope or Vasovagal Attack: This condition is characterized by a sudden onset of dizziness, palpitations, hot flashes, and sometimes a sudden urge to defecate, which matches the patient's symptoms. It's often triggered by stress or certain bodily positions and can be associated with tremors due to the body's vasovagal response.

Anxiety or Panic Attack: The symptoms of dizziness, palpitations, hot flashes, and tremors can also be indicative of an anxiety or panic attack. The sudden urge to defecate could be related to the body's 'fight or flight' response.
Menopausal Symptoms: Although the patient's medical history is unremarkable, the presence of hot flashes could suggest menopausal symptoms. However, the combination with other symptoms like dizziness, palpitations, and a sudden urge to defecate makes this less likely as a standalone diagnosis.
Orthostatic Hypotension: This condition involves a sudden drop in blood pressure upon standing, leading to dizziness and potentially palpitations. However, the absence of notable changes in vitals makes this less likely.

Cardiac Arrhythmias (e.g., Atrial Fibrillation): Although the patient's vitals are unremarkable, cardiac arrhythmias can sometimes present with palpitations and dizziness. Missing a diagnosis of a serious cardiac condition could be fatal.
Myocardial Infarction or Cardiac Ischemia: It's crucial to consider cardiac causes, especially in a post-menopausal woman, as the presentation of heart attacks can be atypical, including symptoms like dizziness and palpitations without chest pain.
Neurological Conditions (e.g., Transient Ischemic Attack, Seizure): Although less likely given the symptom complex, neurological conditions could potentially cause some of these symptoms, and missing such a diagnosis could have severe consequences.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodes of palpitations, sweating, and hypertension. The hot flashes and sudden onset of symptoms could potentially fit this diagnosis, although it is much less common.
Autonomic Dysfunction: Conditions affecting the autonomic nervous system, such as multiple system atrophy or pure autonomic failure, could potentially cause some of these symptoms, though they would be expected to be more chronic and progressive rather than episodic.
Hypoglycemia: Although the patient's symptoms do not classically suggest hypoglycemia (e.g., no mention of confusion or loss of consciousness), it's a condition that can cause tremors, palpitations, and sweating, and is worth considering, especially if the patient has a history of diabetes or is on certain medications.