Mag does help some- nothing to write home about for me- (I’d say it gives me roughly a 10%, maybe 15% boost in energy- and is the only thing I found that really does help some) but my doc warned me to avoid because of the kidney issues- Something about not being able to excrete it like normal people- making it risk for too much magnesium- i don’t really recall now-
I do go very low in D- down to 8 one year- went on high dose- got it back up to where it was ‘sposed to be- D will also cause stones- but i noted when taking with K, it didn’t do it as much-
In my experience, when added to vitamin D and magnesium, the result of collagen peptides was remarkable. After an initial several days of fatigue, my circulation and level of energy improved. Areas of skin on my face turned red and then cleared to new skin. Friends and family described me as looking much healthier, which was how I felt.
Another line of inquiry would be to check for possible GI issues like celiac disease or food intolerances. They can lead to vitamin and mineral deficiencies that have a wide range of effects.
You might want to try an NADH supplement and alpha lipoic acid. They can be helpful with fatigue type disorders.