I'm sorry you've been dealing with this for so long. Have you seen a doctor? If not, you really should.
This could be caused by a lot of different things - it could be a migraine, low blood sugar, low or high blood pressure, or many other things. It's impossible to know without some testing and maybe some imaging.
https://www.healthline.com/health/pressure-in-head
https://www.healthline.com/health/headache/blurred-vision-and-headache
If it's bad enough for you to have to pull over - meaning it is interrupting your daily activities - then it is time to see a doctor.
Let us know what happens!