help! infection

Im 16, and recently i had an itch down there and discovered a white discharge that is coming out of my vagina, so i googled it and it looks like Candide yeast infection...i am worried however i think it might be because my menstrual cyclus is late which is usual because my mom had the same thing and i had visited gyno about it. Never the less i was wondering is it necessary to visit my gyno or can i just treat it with Canesten that i had found at home? How long before it is gone? Should i be worried? Has anyone had a similar experience help a gurl out