Seizure: Given the patient's history of seizures and the fact that she has not been taking her seizure medication for two years, it is likely that her current symptoms are related to seizure activity. The recent event and feeling "off" today could be indicative of a seizure or post-ictal state.

Dehydration or Electrolyte Imbalance: The patient has been using ibuprofen, which could contribute to dehydration, especially if she has been taking it frequently. Dehydration and electrolyte imbalances can cause dizziness and fainting spells.
Migraine or Vasovagal Syncope: Although the patient mentions seizures, her symptoms of dizziness and passing out could also be consistent with migraines or vasovagal syncope, especially if triggered by a specific event.
Anxiety or Panic Attack: Feeling "off" after an event could also suggest an anxiety or panic disorder, which can cause physical symptoms like dizziness and fainting.

Intracranial Hemorrhage or Stroke: Although less likely given the patient's age and history, it is crucial not to miss a potential intracranial hemorrhage or stroke, as these conditions are medical emergencies.
Cardiac Arrhythmias: Certain cardiac conditions can cause dizziness and fainting. Given the patient's symptoms and the fact that she has had similar episodes in the past, a cardiac cause should be considered.
Infection (e.g., Meningitis): An infection affecting the central nervous system could present with seizures, dizziness, and a general feeling of being unwell.

Mitochondrial Disorders: Given the patient's history of seizures and the fact that these episodes have become less frequent over time, a rare mitochondrial disorder could be considered, although this would be less likely.
Autoimmune Disorders (e.g., Anti-NMDA Receptor Encephalitis): These are rare conditions that can cause seizures, altered mental status, and a variety of other neurological symptoms. They are important to consider in patients with unexplained neurological symptoms.