What Causes Frequent Headaches And Blurred Vision?

I have been having headaches more frequently over the past few months. They often happen towards the middle to end of the day and the cause me to feel nauseous. Recently my vision has been off as well, things like blurry and dull vision. the headaches don t last long, normally I have to sleep to get rid of them, medication doesn t seem to help. The vision is a constant problem. I am not a very stressed person. my speech I have noticed it becoming worse, but not quickly. things such as mixing my words when I am speaking and almost not being about to say what I am wanting too, as well as mixing words/numbers up when writing or typing. I am seeing a doctor within the next week or so but I want to know what someone else might think it may be. I am an 18 yr old female, very active and fairly healthy eater.