I dont know why zink causes nausea generally, but i think it should allways taked with food and not empty stomach. Zink compete with mercury,copper and cadmium so if one have a lot those it might cause bad detox and retoxification. Did you have mercury or cadmium high at all in your test ?
I think i even saw warnings to not take big doses of zink if have bad mercury load, i dont know is the warning valid thought, or how then get mercury out ,becouse good nutrients should be the best and safest method to detox heavy metals out ?
I get fatigue and brain fog if take a lot zink, it do seems to help with Depression thought and stomach also.