The odds of a yeast infection affecting your brain is very very slim. Of course there are other health problems that it can cause, and I'd be looking to get rid of it asap. I also wouldn't get the medicine from talking with a pharmacist, but instead, you should look to visit your OB/GYN and have it looked at. What if it's not a yeast infection, but another infection? The only way to know would be for your doctor to take a good look and ensure that it's what you think it is.