Just reread this entire thread and my posts/answers on stress management, nutrition and sleep. You will have 90% of your questions answered afterwards.
In regards to nutrition I do want to mention that minimizing gluten, eggs and dairy consumption can work wonders for your chronic fatigue. These compounds are usually not problematic by themselves (not taking into consideration celiac disease or lactose intolerance fyi), it’s the Epstein barr virus that’s causing trouble. It feeds on these compounds and creates neurotoxins and dermatoxins in the process. When these neurotoxins attach to your neurons and start oxidizing, they can shortcircuit them, resulting in compromised neurotransmitter production and transmission.
Instead, bring more fruits, vegetables, herbs/spices and wild foods into your diet to support serotonin production, reduce cortisol/adrenaline output and restock neurons with material for neurotransmitter production and transmission (fruits and vegetables are packed with vitamins, minerals and phytonutrients that neutralize harmful toxins, reduce inflammation and act as cofactors or co-enzymes in the production of neurotransmitters. They also provide electrolytes like sodium, potassium, calcium and magnesium which are absolutely critical for neurotransmission (refer to action potential via sodium potassiump pump).
It probably isn’t. Normally I’d recommend a diet break of 2 weeks minimum, even longer if you have been dieting for 12+ weeks and if your weight keeps going down. Under normal conditions, your weight starts stabilizing within 2-3 weeks. After that, you should be good to start a new cycle of fatloss (if you need it), maintain your current weight or start eating in a surplus to grow muscle and enhance recovery.
Eating in a caloric deficit is imposing stress on your body. Sleep deprivation, not feeling well or not feeling like yourself, having high cortisol levels are all signs that you need to take a break. There’s a time and place for cutting but it’s far from ideal when you are physically and mentally stressed out. Believe me, I’ve been there. It’s not fun or effective at all.
You should actually deload during your diet break. That’s a good combination to enhance recovery. Eating more nutritious food and reducing overall training volume will help you get better. Work on your sleep too. Try to view the low solar angels (sunrise and sunset) during the day. This will help stabilize your circadian rhythm and reduce the negative effects of evening blue light exposure. Eat your last meal 3 hours or more before bedtime. Stay consistent with your sleep schedule. 30 minutes deviation from your usual wake and sleep times and the occasional late night out is fine but no more than that until you start to feel better. Don’t underestimate the power of a supportive, fun social environment. Spending quality time with friends and famlily is very good for stress management.
Ultimately I look at this way: you can eat well, sleep well and train smart but when you are dealing with issues on a subconscious level that cause you stress, you need to figure that out and fix it as soon as possible. Diet, sleep and exercise will support you but they are not enough to get rid of chronic stress/fatigue IF you are dealing with lots of mental stress. Even if you’re not stressed out psychologically, the physiological stress you impose on your body also affects your nervous system. When the nervous system is taxed too hard, problems start to arise. Deloading and a diet break are surely the right actions to take at that point.