You could try taking some coconut oil. It is a good antifungal and and antiparasitic. It is also a great help for those with constipation. Don't take too much though, as you might need to use the bathroom too many times a day. Perhaps 2 or 3 teaspoons a day though might be beneficial.

As for vitamin c and getting enough magnesium, one could take their vitamin c as magnesium ascorbate, thus getting both magnesium and vitamin c together in a form that is well absorbed.