Hyperthyroidism/gravis disease be the cause of extreme muscle pain?

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[CCF-Neuro-M.D.-JT]

There's a number of things that could possibly be going on.  Thyroid disease in itself, typically hypothyroidism, is well known to be associated with muscle cramping and weakness. Medications used to treat hyperthyroidism like PTU and methimazole have been reported by a group in Japan to cause severe cramping and muscle problems.  Finally, there is a muscles disease called stiffman or stiff-person syndrome that can be seen in women your age which presents with diffuse cramping.  It is also associated with thyroid disease and is thought to represent an immune response against a chemical in your body that helps to relax the muscle (very simplistically speaking). It's diagnosed with a blood test, clinical exam, and EMG.

As the cramping is getting worse, consider getting a neurological examination, bloodwork to look at muscle proteins like CK and aldolase, electrolytes, and possibly the anti-GAD antibody (for stiffman, depending on your doc's exam findings and clinical suspicion), and an EMG to help sort things out. Good luck.