Exertional Rhabdomyolysis: This is a common cause of rhabdomyolysis, especially in individuals who are not accustomed to strenuous physical activity. Given the patient's morbid obesity, even relatively minor physical exertion could lead to muscle damage due to the increased strain on muscles.

Medication-Induced Rhabdomyolysis: Certain medications, such as statins, are known to cause rhabdomyolysis as a side effect. Given the likelihood of comorbid conditions in a morbidly obese individual, the use of such medications could be a contributing factor.
Severe Hypothyroidism: Although less common, severe hypothyroidism can lead to muscle damage and rhabdomyolysis. This condition might be more prevalent in individuals with multiple health issues, including obesity.
Electrolyte Imbalance: Electrolyte disturbances, particularly those involving potassium, sodium, and calcium, can predispose to muscle injury. In a morbidly obese patient, various factors including diet, renal function, and medication use could contribute to electrolyte imbalances.

Compartment Syndrome: This is a medical emergency that can cause rhabdomyolysis due to increased pressure within muscle compartments leading to muscle and nerve damage. It requires prompt recognition and treatment.
Toxin Exposure (e.g., Cocaine, Amphetamines): Certain drugs can directly cause muscle damage. Given the potential for substance use in various populations, this diagnosis should not be overlooked, especially if there are suggestive symptoms or signs.
Infections (e.g., Legionella, Influenza): Certain infections can lead to rhabdomyolysis. Identifying and treating the underlying infection is crucial for patient recovery.

Muscular Dystrophies: While more commonly diagnosed in childhood, some forms of muscular dystrophy may present later in life and could potentially lead to rhabdomyolysis, especially with strenuous activity.
Mitochondrial Myopathies: These are a group of disorders that affect the mitochondria, leading to muscle damage under certain conditions. They are rare but should be considered in the differential diagnosis of rhabdomyolysis, especially if other causes are ruled out.
Malignant Hyperthermia: This is a rare but life-threatening medical emergency triggered by certain drugs used for general anesthesia. It could be considered if the patient has recently undergone surgery or been exposed to triggering agents.