Obviously, seeing a doctor for prolonged itchiness is the best course of action. In the meantime, getting an OTC preparation like Vagisil is also a good alternative.
One good temporary remedy is to get Vagisil wipes, which are pre-moistened disposable cloths, and put them in the fridge for an hour or two. Applying the cold cloth on the itchy skin is a little bit of Heaven for someone who has been miserable. The itch stops almost immediately, and the cool cloth helps soothe the irritated skin.
Some women douche when they have itching, but this is not always recommended since, if they go to the doctor, the ingredients in the douche can alter the results of a vaginal swab.