Scarlotte,
 
I have prayed for your husband, Christopher.  I understand his CAT scans came up negative.  Have the doctor's considered if he's allergic to anything?  I've been sick, too.  The CAT scans and other tests also came up negative.  So the last Doctor I saw suggested I might be allergic to something like air fresheners or scented candles.  I guess there's lots of chemical stuff we can be allergic to.  Anything new in his environment could be a factor.
 
Joe