one thing that significantly helped my fatigue & dizziness was sleeping at the same time every night. it helped my brain to figure out which hours i needed to be up & awake. i'm also on a stimulant, (also very very helpful energy-wise) and, listen hear me out on this one, raise the head of your bed. (like a hospital bed), this has many benefits in pots patients, i don't know all of those benefits but trust me, search it up :)