dural calcification and tremor

I have lupus (SLE) and recently diagnosed with autoimmune thyroiditis causing hypothyroid.  I have also had restless legs for a long time.  I recently and very suddenly developed tremors and cognitive dysfunction in direct proportion to the severity of the tremor.  It always followed what I would call a restless leg feeling in ALL of my body.
I was alarmed and visited my doctor right away who sent me for a CT scan.  The report was as follows:

The ventricles appear normal in size and configuration.  There is no evidence of hydrocephalus and no focal mass effect or midline shift.
Mild dural calcification is noted incidentally at the vertex which is an incidental finding.
No focal intracerebral areas of abnormal attenuation or pathological enhancement are identified.  No evidence of a space occupying lesion or acute intracranial haemorrhage is detected.  No focal cerebellar could be identified.

They said there was no sign of a cause of my symptoms so they did a further MRI which found nothing but sinusitis.  

What is the calcification and why did it not show on the MRI?  And why does it have nothing to do with my symptoms?  
My GP cant give me any reasonable ideas of what it could be, she is just hoping that the thyroid medication will make it go away but I have seen zero improvement.  I am very worried about the symptoms as it is important I keep my job and tremors make it very hard to work, drive or do much of anything.  Let alone answering the phone and being unable to remember my name!  I dont expect an online diagnosis but some ideas or suggestions that I could point my doc in the direction of, as she is baffled.