Vasovagal Syncope or Near-Syncope: This condition is characterized by a sudden drop in blood pressure, leading to reduced blood flow to the brain, which can cause dizziness, lightheadedness, and a feeling of being unsteady. The symptoms presented, such as dizziness, not walking straight, and a wobbly gait, are consistent with this diagnosis. The recent menstrual period could also be a contributing factor due to potential hormonal changes or dehydration.

Migraine: Migraines can present with a variety of symptoms including dizziness, vertigo, and pressure in the head. The "something strange" feeling in her head could be indicative of an aura phase of a migraine.
Anxiety or Panic Attack: Anxiety and panic attacks can cause physical symptoms such as dizziness, lightheadedness, and a feeling of pressure or discomfort in the chest or head, which might be perceived as strange sensations.
Dehydration or Electrolyte Imbalance: Given the recent menstrual period, dehydration or an electrolyte imbalance could contribute to feelings of dizziness and weakness.

Stroke or Transient Ischemic Attack (TIA): Although rare in teenagers, a stroke or TIA must be considered, especially if there are focal neurological deficits. The sudden onset of dizziness and wobbly gait could be indicative of a cerebrovascular event.
Intracranial Hemorrhage or Mass: Conditions such as an arteriovenous malformation (AVM), tumor, or hemorrhage could present with sudden onset of headache, dizziness, and neurological symptoms.
Meningitis or Encephalitis: Infections of the meninges or brain can present with sudden onset of headache, fever, and neurological symptoms including dizziness and altered mental status.

Multiple Sclerosis: This autoimmune disease can present with a wide range of neurological symptoms, including dizziness, vertigo, and ataxia, although it is less common in this age group.
Chiari Malformation: A structural defect in the cerebellum that can cause symptoms such as dizziness, balance problems, and headaches, especially with coughing or straining.

Immediate Assessment: Vital signs, neurological examination, and assessment of gait and balance.
Laboratory Tests: Complete Blood Count (CBC), Electrolyte Panel, Blood Glucose, and Urinalysis to rule out infection, dehydration, or electrolyte imbalance.
Imaging: Consider a non-contrast CT of the head if there's suspicion of hemorrhage or mass. An MRI might be more appropriate for evaluating structural abnormalities or multiple sclerosis.
Further Evaluation: Depending on the initial findings, consider cardiology evaluation for potential cardiac causes of syncope, neurology consultation for migraines or multiple sclerosis, and psychiatric evaluation for anxiety or panic disorders.

This approach ensures a comprehensive evaluation of the patient's symptoms, considering both common and potentially life-threatening conditions.