This link may help you learn more about subarachnoid hemorrhage, bleeding in the brain (aneurism) and other things mentioned above: http://www.nlm.nih.gov/medlineplus/ency/article/000701.htm .
I suggest you see a Neurologist to be evaluated. Some of your symptoms could be a migraine but you need to be examined.
Do any neurological problems run in your family and have you hit your head?
Lol, pretty much all of that is contained in my question, but just for a reiteration:
Yes, I could feel that it was about to happen.
I experienced nothing but extreme pain.
It was only on the left side.
It lasted about two minutes tops, but more likely only about one.
It was too quick to do anything to stop it.
The usual recommendation for a patient like you is to go to the hospital immediately when this strikes. The reason for that is that a subarachnoid bleeding (brain bleeding) presents just this way; an extremely painful headache that comes on very fast out of the blue.
Obviously you didn't have that since you are still alive. You probably have primary stabbing headache or a strange type of migraine or similar.
Patients who have had this before don't have to go to the hospital when this happens since they have had it before and know it is nothing dangerous.
What you could do is to check for brain aneurysms since they sometimes bleed a little bit, causing pain, weeks or months before they eventually burst for real. This is probably not necessary in your case and it is very unusual. But still, you can talk to your doctor about it and maybe he/she will order a MRA or CT-angiografi of your brain, just to be sure. But I wouldn't worry about it. It is always good to take to your doctor though.
Take care!
Did you know the headache was going to come prior to it coming? Did you experience any of the following with the headache: nausea, light or noise making the headache worse, a pulsating feeling to the head, only 1-side of your head was affected, any paralysis or weakness to half your body, visual changes? How long did the headache (H/A) last? Did you do anything to make the H/A go away? What do you think triggered the H/A?