Ophthalmic Migraine problem?

Ever since I was in 7th grade I have had on and off zig zaggy lines in the peripheral of my vision for 15-20 minutes. I am 14 now and I am sick and tired of going through this 2 times every single month. Its like my brain has a calender and it sets a day out of each month to put me through 15 minutes of hell. It happens at the worsts times, like at school, hanging out with friends, or whenever I am in a position to not be ready for something like this. I don't know what to do! Is there a treatment, or some technique to make these episodes not happen as frequently? Please help me!