I get it frequently with illness, periods, stress or being run down. I also get facial and spinal neuralgia.
fatigue wise, it sounds boring but - good sleep hygiene, good food, multivitamins and iron (‘gentle iron’ if it makes you ill) etc.
get bloods done to see if you are actually run down on anything. Iron levels or even iron stores being low can massively impact fatigue and energy.
I plan my days to help my energy stores. I know I can’t do what I used to so
what can I automate, delegate, delete etc.
online shopping instead of traipsing around shops.
batch bake some simple dishes when you can. One for now - one for freezer.
can others help around the house.
sometimes a home yoga session or something (gentle) helps me by stretching out and just slow gentle movements to keep my body engaged.
had this for over 10 years now due to severe stress and trauma. Good luck.