My chiropractor suggested I take magnesium and zinc for the following:

Magnesium: for stiff muscles, heart palpitations.

Zinc: because I have a low sex drive :(

He said to take them both on an empty stomach. I do fine with the magnesium on an empty stomach, but the zinc makes me vomit.

How long before I can expect results?
How long should I go before and after taking the magnesium to eat?
Is it useless to take the zinc if I have to take it with food?