The itching would not have lasted this long just from iritation. You need to go to a gynecologist and find out what is causing the itching. It could be a yeast infection - a bacterial impbalance in the vaginal tract. That would need some medication to get the itching to go away- but fortunately, the medication can be taken and the itching cured after a three day regime. There are other ways to address the issues as well.
It may also be some other problem-there is no way for me to know for sure. So- don't delay. The best thing you can do for yourself is to go to a gyncologist and get a laboratory test to find out for sure.
Is the itch inside your vagina? Itching is the most particular sign of a yeast infection. Some "cottage cheese" like discharge may be present, but not always. I would make an apointment w/the doctor, especially if you've never had a yeast infection before.(Just for proper diagnosis.) Or you can try and get monistat 7 at the local pharmacy and treat yourself to see if that helps. But I would recommend going to the doctor since it is your first