I suffer from migraines. I normally get the "aura"?

When I get the aura I can usually take aspirin or Ibuprofen in time to prevent the pain. Once in a while my eye will feel like it is becoming surrounded by darkness making me feel really strange. It normally goes away within a few minutes. I had one today and it took almost 30 minutes to go away, letting me see again. I have a small headache, but nothing big so I am not sure if this has anything to do with a migraine. Does anyone else get this "dark blindness" before a migraine? If this has nothing to do with my migraines then I am in trouble because it is related to the brain..and I have no insurance. Any info would help.