Okay, I'm going to quit trying to be funny for a while. (And really, if I'd thought of this earlier, I would have posted it.)
I have 'migratory' arthritis. It's like an aimless wino—hits a different joint every couple of hours. I can wake up feeling great, and by 10:00 am not be able to use my left hand at all. At 2:00 pm my hand might be fine, but my right big toe hurts like hell. It's not restricted to joints; sometimes it shows up as a muscle or tendon malfunction. The reasons that I didn't suggest this before are that you didn't mention any pre-existing problems (arthritis usually escalates from some minor discomfort over a matter of years) and because of your description of the pain. I hadn't accounted for the fact that people have different pain thresholds. What one person considers incapacitating pain might be a minor nuissance to another. My tolerance happens to be pretty high, so I didn't think of arthritis when you described how excruciating your pain was. (Then again, I played baseball for 5 weeks with a broken finger and it didn't bother me.) Anyhow, it might be worth looking into. You'd be particularly succeptible to it if you have any other autoimmune disorder such as diabetes or lupus.
Another possibility would be fibromyalgia. Last, but not least, there is something that's simply called 'chronic pain syndrome'. No one seems to understand it very well.
I strongly urge that you consult a physician. Some conditions similar to yours are merely indicators of something more serious, such as a heart problem. At the very least, you might get a prescription pain medication.