I had it, and it improved with lots of sugar, and carbs in general etc.
I do believe today that it's really not as difficult to treat as some say, it's a cortisol dysfunction, actually a problem with the hypothalamic - pituitary - adrenal axis, people get it from different things, but basically you need to get your hands on the parasympathetic nervous system in some way, it usually starts taking over with carbs, stimulation like spike mats, massage, acupuncture needles, and then you start to relax etc... after it overrides the stress (sympathetic system), you will start "healing".
Specific nutrients are good, you just need to know what to target, and also the body uses more of certain vitamins when stressed, also salt, potassium, magnesium, calcium balance is important so that you start to relax.
The problem is that when you get stressed, it gets hyper, and you can't get "down" (parasympathetic response) like a normal person after the stress, so your cortisol output changes, it gets high in the evening, low in the morning, and so on.
But all in all, the solution differs, but I would try to cut off the stress loop with something that works for you.
Also, do not believe anyone who says that there is healing period where you will feel like shit, you will feel great, and relaxed (!) right away when you find a system that works for you. Not great as in yeah, whoa, more catecholamines, up we go, but great as in just had the best the sleep ever, and feeling all relaxed.