Headaches, vertigo, and numbness of the extremities = something serious?

  : For over 10 years I've lived with vertigo, and was in fact diagnosed with chronic vertigo, prescribed medicine, and told "learn to live with it."  I've also been living with numbness in my hands, and feet - nothing disabling, but more annoying than anything else.  Lately, I've been suffering with severe headaches - my family practitioner diagnosed them as combination tension and migraine headaches.  Several medications have been tried - Midrin, Amerge, Imitrex, and Soma.  None have worked on a regular basis, and the headaches are getting worse.  I now experience a severe headache on a daily basis, which affects my daily activities.  I saw a neurologist last week, he did extensive physical examinations, and an EEG which came back normal.  He has ordered MRIs with and without, and a spinal tap.  He seems to think my vertigo, numbness and headaches are interrelated, and as he put it "something more serious than migraines."  He wouldn't say what his diagnosis was at this point in time - can you shade some light on this issue? What illnesses, or diseases can be related to vertigo, numbness and migraines?  What could he hope to find from a spinal tap?  Thank you for any help you can give me on this matter.
  I think I needed to add that my headaches began within weeks of being put on estrogen.  June 1997 I had a partial hysterectomy - uterus and left ovary and fallopian tube were removed.  March 1998 my remaining ovary and tube had to be removed.  I began estrogen replacement in the form of Ortho-Est 1.25 mg daily.  It has since been cut back to .625 but the headaches remain.
  I also suffer from visual disturbances in combination with my headaches - usually blackness in my peripheral vision, black spots floating before my eyes, auras or halos around objects and general blurred vision.  Photophobia, and sensitivity to sound occur in conjunciton to the headaches.  I feel extraordinary amounts of pressure behind my left eye when the headaches occur. 80% of the time my headaches are sharp piercing pains located on the left side of my head throbbing with each pulse.  10% of the time my headaches radiate from the right side of my head and move to the left ending with the headaches I described above.  The remaining 10% of the time my headaches begin as a tightness and pressure in the back of my neck, moving up the back of my head and ending in the left front lobe of my head.  All headaches end in the left front area causing the above listed symptoms.  
  What can this be?!
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Dear Kelly,
thank you for your question, and sorry for the delay in replying.
Your headache sounds like a combination of tension and vascular
(i.e. migraine). Hormone theraphy may cause headache and it is
possible that the hormone contributes to this chronicity.
More importantly is the combination of symptoms (vertigo =sensation of
room spinning, numbness, and  chronic headache) which may
be caused by either inflammatory disease of the central nervous system or chronic infection of the covering of the brain.
By performing Lumbar puncture,  your doctor can examine the cerebro
spinal fluid for evidence of inflammation and/or infection. In addition they
can also test the fluid for multiple sclerosis, which can also cause
numbness and vertigo./
I hope this helps. Good luck.