Fatigue is a big problem for me too. Nervous system is constantly on high alert, so there are limited resources left over for basic self-care. I think running on fumes becomes so familiar we start to think it's normal. Exhaustion hits suddenly and out of nowhere it hurts just to walk or think or hear someone speak in the next room.
Things that have helped me: meditation, randomisation of inconsequential decisions, working really hard to improve interoception so it doesn't come 'out of nowhere' and I'm more conscious of the factors involved, strategic use of noise-cancelling headphones, self-directed CBT around stressors.
It is a profoundly unpleasant experience. I hope it gets better for you soon.