Before i come on my cycle. my vagina itches really bad. ..what does that mean?

Hormones :(: The hormone changes that occur right before menses can cause a change in the vaginal lining. It can also change the acidity of the vagina, causing itching and even a temporary growth of vaginal yeast and bacteria. Be sure you are not wearing tight-fitting clothing and don't use douches and other internal products, because they can make the problem worse. Next time this happens, see your doctor.