Answer:
c. Thyrotoxicosis
Explanation:
According to my research on studies conducted by various medical professionals, I can say that based on the information provided within the question the differential diagnosis should include Thyrotoxicosis. This is because this refers to an elevated amount of thyroid hormone within the body and can cause hyperthyroidism, which includes symptoms such as irregular heartbeat and brisk reflexes. It can even cause hair loss which may also explain why her hair doesn't stay wavy anymore.
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