CFS is an outdated name as medical knowledge has moved on from then when it was a default diagnosis-i.e. we don't know what is wrong, so we'll call it a syndrome, and name it after one of the numerous symptoms, even though it is not a common one.
The proper name now is ME (Myalgic Encephalomyelitis.)
There are tests that can be done to see if you have it.
If your doctor says you have CFS, change doctors, as he/ she would be a waste of time.
Have a good look at this website to find out all you need to know about ME-symptoms, treatment, diagnosis etc.

http://www.hfme.org/testingforme.htm