Try to get prescription from your gynecologist.and don't to forget rest
You mentioned magnesium? What dose?
Sorry i meant Drug for iron
If You talk about fatigue a bog fatigue it is due to pregnancy.in last monthes baby consumption of your reserve be more and more .so try to eat welle especially fruits vegetable and chicken milk yogurt food of sugar long like complete bread ...eat also small quantity of nuts.water drink lot.and take magnesium drugs for fee don't forget the 6month ample of vit d.
Nausea may happen at this stage of pregnancy.so all this symptoms are due to pregnancy