Okay, I understand this likely not what you were expecting as an answer, but this is based on my own personal experience as well as reading I did before changing my way of eating (specifically the meta-analysis of dozens of scientific papers in Gary Taubes "Why We Get Fat")

Switching to a keto diet (under 20 net carbs a day) had an immediate and lasting effect on my mental acuity, mental health, energy levels, and overall wellness. I had persistent brain-fog stemming from stress, overwork, bad health habits, and a case of Mumps which left me feeling like a shadow of my former self.

Within 36 hours of changing the way I ate, I felt like I was finally back to myself. I had my quick wit, energy to dig into problems, and a desire to move and do things instead of rest, eat, and wallow.

I'm happy to talk more about it if you're interested, but I'll keep this brief and simply say that trying a 3 day experiment where you keep net carbs (carbs minus fiber) under 20 per day may have a dramatic effect and give you the energy to begin to address other root causes.