Doctors are stumped 1 of 50 with rare disease?

My husband was hospitalized for over 5 days and doctors are stumped at what he has.  over a week ago it started with stroke like symptomd, loss of feeling in BOTH arms and BOTH Legs, paralysis of the face and unable to speak.  Then it was followed by confusion.  He could not comprehend what anyone was saying and did not know what day it was.  He then would get a stabbing headache that caused him to vomit.  This would last anywhere from 6-12 hrs.  He had 6 episodes in 8 days.  First time at hospital he was admitted.  CAT scan, MRI, MRE, Blood test were normal.  Doctors passed it off as complex migraine.  The 6th time this happened within a week he said the pain was worse.  Took him to ER and he stayed at hospital for 5 days. Was given Divalproex Sodium.  This helped and he did not have any attacked however, had one when they tried to take him off.   Cat scan, MRI and bloodwork were done again and came back clear.  They then decided to do spinal tap.  The CSF was abnormal.  Nucleated count 420, Lymph 98 protein 199.  Was told now his symptoms were not migraine related and this is serious.  Neurology now think it is  something viral but it will not be days until we get results.  Was told it could be a rare meningitis that only 50 cases ever reported.  Please note he did not have fever or stiff neck.  Please help if you have any insight on these issues.  Thanks!

[akn812]

Forgot to mention.  The episodes always happen when he wakes up or sleeping.