Hypokalemic Periodic Paralysis: This condition is characterized by episodes of muscle weakness and paralysis, often triggered by high carbohydrate intake, insulin release, and subsequent potassium shift into cells. The patient's symptoms improving with salt intake (which can help increase potassium levels indirectly by reducing potassium shift into cells) and the context of being physically active and having diabetes support this diagnosis. The recent introduction of creatine supplements, which can affect electrolyte balance, further supports this possibility.

Exercise-Associated Hyponatremia (EAH): Although the serum sodium level provided is 133 mEq/L, which is at the lower end of normal, EAH could still be considered, especially given the patient's recent increase in physical activity and the use of creatine supplements. However, EAH typically presents with more profound hyponatremia.
Dehydration and Electrolyte Imbalance: The patient's active lifestyle and potential for excessive sweating could lead to dehydration and electrolyte imbalances, including sodium and potassium disturbances, contributing to weakness and syncope.
Adrenal Insufficiency: Though less common, adrenal insufficiency can cause hyponatremia, hypotension, and weakness. The improvement with salt intake could be related to the mineralocorticoid effect.

Cardiac Arrhythmias: Conditions such as long QT syndrome or other arrhythmias could cause syncope and might be exacerbated by electrolyte imbalances. These are critical to rule out due to their potential for fatal outcomes.
Hypoglycemia: Given the patient's diabetes, hypoglycemic episodes could cause weakness and syncope. The improvement with salt intake might be coincidental, and hypoglycemia needs to be considered and ruled out.
Severe Hypokalemia: Even if not part of periodic paralysis, severe hypokalemia can cause muscle weakness, arrhythmias, and syncope. It's crucial to check potassium levels during and between episodes.

Bartter Syndrome or Gitelman Syndrome: These are rare genetic disorders affecting kidney function, leading to hypokalemia, alkalosis, and sometimes hypomagnesemia. They could potentially cause the described symptoms, especially with the triggers of exercise and dietary changes.
Thyroid Storm: Though typically presenting with hyperthyroid symptoms, a thyroid storm can cause significant electrolyte disturbances and could potentially lead to the symptoms described, especially in the context of significant physical exertion.
Pheochromocytoma: This rare tumor of the adrenal gland can cause episodes of hypertension, tachycardia, and syncope, sometimes triggered by physical activity. Electrolyte imbalances could contribute to the patient's symptoms.