I was diagnosed with Epstein Barr Syndrome 22 years ago at the age of 54. B12 shots every week; chiropractic adjustments, and acupuncture helped me a lot. In retirement I had 11 really good years, increased physical activity, etc. Then 14 months ago the illness began steadily to take over again. Along with the two most prevalent symptoms (fatigue, muscle-joint discomfort) I have a couple different symptoms this time -- muscle spams and "Charlie horses" in legs. Yes, it seems to be a different "bird" now that I am 76. Recently I've been to a rheumatologist -- his suggestion of using COQ10 hasn't helped; he also suggested two prescriptions (Celebrex and Cymbalta); but I felt they were too expensive for me to try only to find out they don't work. Instead I am going to try acupuncture again. I very much understand the problem of "just not feeling good." I really understand your husband's situation because I was there. It caused me to take 3 short FMLA breaks from my employment; now it really interferes with things I'd like to do and even things I have to do just to take care of myself. I wish your husband well.

My father experienced the same some years ago. He always stated he was tired. My mum found it abnormal and took him to doctors. As a result, they found he suffers from "apnea" which prevents him from breathing well when sleeping due to night breth-gaps where he suddenly stops breathing for short periods of time. Therefore, oxygen levels and rest are abnormal.
He now sleeps with a mask which pushes the air of the room right to his nose and mouth so he takes it all and breath. He deinflated and his face completely changed.
Visit a neumologist.