I get really sick on my period, am i lacking some sort of nutrition?

Iron shortage?: When you bleed, the body loses iron. If you already have a shortage of iron, the loss of blood can make you feel weak. There may be other causes as well but best way to know if there is a nutrition-related problem is to be evaluated by physician.

Sick?: Does 'sick' mean nauseous? If so i'll give you a different answer: this is a common side effect of prostaglandins, which are produced in very high amounts during menstruation. Could eb other possibilities, too.