I think I have only ever had one migraine before and it was bloody strange.
Now I have another, and at least I know it has happened before and will pass.
What is strange is that it is a visual effect, and this time it has started right in the middle of my vision (so I am kind of typing this blind). It does mean I can actually see the effect this time though, as last time it was slighlty off centre and you can't look at something off centre when it is all in your head.
It appears to be both eyes, i.e. the effect is clearly not actually in my eyes but in my brain.
The best way I can describe it is like looking through some sort of strange cut glass, with lots of sharp angles and colours all in front of what you are looking at. The colours are like the colours on the edge of a prism - sort of not quite really there. It started as a dot and is getting gradually bigger and bigger. It is flashing, and I am sure I have seen the effect on an old BBC micro before now with the alternative red/green flashing colours and random triangle plots.
Also, a headache - not too bad, but getting worse, and a feeling of being spaced out.
I would go home, but I cannot see that working well on a bicycle.
It is damn strange trying to read this as I have to read it off centre with what vision I still have.
Last time it lasted maybe half an hour. Lets hope not too long this time.
Hmm, now it is bigger I can tell it is only my left vision, and the headache is only on the right.