You have mentioned fasting.

Depending on the person, some people's mood swings into hypo or mania with fasting, esp fasting for more than a few days. Some people initially feel ill with all kinds of symptoms (often withdrawal) and mood issues upon starting a fast. Still others get "high," especially after a prolonged fast. I know of spiritual gurus and their followers who fast in order to reach and to maintain the eventual "high." Diet can definitely play a role in mood or mood changes.

You have mentioned supplementing with zinc. I know when I had first started to learn the benefits of zinc, I was tempted to think the more zinc the better. I was wrong, of course. I do not mean to imply you are not taking the right amount of zinc, as there are also likely many differing opinions on which daily intake amount is best! Lol!
Here is a reference showing the uses for zinc, what is considered a safe dosage and what are the effects of taking too much zinc. I just find it very interesting that so many symptoms can be caused by ingesting too much zinc. Zinc — Consumer

While we are told zinc supplementation may be helpful for depression, other sources say the amounts suggested in such studies cause other medical symptoms.
Here is just one study citing zinc as helpful when using SSRI meds. Effects of Zinc Supplementation in Patients with Major Depression: A Randomized Clinical Trial the zinc level here is higher than the table shown above; yet, is much lower than many people ingest daily.

The info behind Vit, D is similar, in that some sources suggest blood concentrations much higher than do other sources. It is quite possible any of our conditions, psych and physical are being complicated by the use (side-effects) of some of the supplements we use in hoping to help ourselves, The info is so often confusing due to the contradictions. I tend to use the recommendations used by the Vitamin D Council : vitamindcouncil (dot)org (They could also be very wrong.)

Just some food for thought for all of us as we sort out our moods and our symptoms.

I know when I start to have too many symptoms to sort out, I usually start an elimination type of a diet. I can often find different foods triggering or causing IBS, congestion, extra fatigue, asthma, mood changes, changes in vision, increased noise sensitivities, etc. the list can go on and on. That's my own experience. I cannot be sure of what others experience when they cut back and/or omit certain supplements and/or foods.

Just one of many thoughts/experiences which caused me to wonder about this is the fact that, years ago now, one of my nephews would totally change in mood/demeanor/personality when allowed to eat a certain type of flavored tortilla chip. The changes were drastic. He was a total mess and everyone around him suffered as well. I have had pdocs warn to watch diet, to keep diet consistent, in order to help to keep mood stable.

I guess I am just sharing the many different factors which can change our mood and even anxiety level, as well as could give us more physical symptoms.

There was a book written about the behavioral effects of many different substances. These are substances we tend to ingest. The reactions can be very individualized. It was a brilliant book. I have found this to be a major factor in my own life, as well as for people in my family. If I can think of the book/author I will share here.

I hope you find some helpful answers soon. I do believe things can get much better for you. I tend to think complicated challenges often require a multifactorial approaches.

You are not alone here. We care! .