I had incredible fatigue.
It turned out I had;
chronic fatigue
low iron
low copper
not enough protein
over training
not enough sleep
Not in that order.
Most of mine is the CG but adequate protein intake helped Majorly, plus not over training. I started to sleep 8 to 9 hours a night, rather than 7.
Im still working it out .
The iron helped as well. Its a good test to have. I also started taking herbs prescribed for me( panax ginseng, shizandra, and some others).Ginseng is great!
Also see if they can check for adrenal fatigue.Thats quite common nowadays,what with stress and working too much.