I believe that the Epstein Barr Virus lays dormant in the system and resurfaces as chronic fatigue syndrome CFS

A misaligned Atlas causes fatigue and fibromyalgia

Candida also causes fatigue/fibromyalgia

Lyme Disease also causes fatigue/fibromyalgia

It's possible to have all 4 conditions or any combination, those diagnosed with "ms" describe it as suddenly having the plug pulled out.

I am very lucky I have never suffered from fatigue, but I think that I may be immune to EBV I haven't even had Chickenpox.