I have been very lucky in my life to not suffer from headaches very often. In fact, unless there is a low pressure system coming in fast, or I've imbibed too much, I never get headaches. However, it appears I do suffer from visual migraines.
They can be quite scary - coming on when you least expect them, and lasting for around 20 minutes. At first I thought it might be a stroke, which was of course - terrifying! I do not have any pain, just a feeling of not being able to see well for a time afterwards. Below is a video of what one may look like. If you have these symptoms it is recommended that you have them checked out, but I was relieved to read they are fairly common, and generally do not require medical attention: