"I take a calcium-magnesium-zinc supplement every day "
This combination is a no no in my experience. The calcium neutralize the stomach acid needed for the uptake of these two; magnesium and zinc.
magnesium and calcium are antigonists.
If you dont believe me; try to take a therapeutic dosage of magnesium and zinc at the same time; like 2-300 mg of magnesium, 50 mg of zinc, Without the calcium. It will probably produce a nausea within 5-10 minutes, and you will throw up all you ate the last hours.
These two minerals need to be taken at different hours, if high dosage. Multi minerals / mixed minerals frequently doesnt work because of it calcium contents. (carbonate as well as phosphate)
-also because the supplement are rather low in both, like 15 mg of zinc 100 mg magnesium in wrong / insoluble form like magnesium oxide.
The calcium in supplements is frequently the factor that prevents uptake and utilization.
-this is also what prevents the zinc-magnesium to not react in a multiple supplement, and also, probably, why you have no effect of it.
It took me years to find out of magnesium, to have effect of it.
The stomach acid need to be working (low ph) then the vit B6 are needed for magnesium and zinc uptake. When I got it all together, years of indigestion disappeared in days:)