Sounds like classic temporo-mandibular joint dysfunction to me.
I'll merge this into the main thread so you can have a read of other peoples' experiences - in the meantime look after it, avoid eating anything too chewy and try to resist the urge to click it! If you can keep it in the correct position for long enough it should start to work more normally on its own - the main thing is to try to avoid using your extra range of motion so it doesn't become normality.
If it still hurts in a day or two or the pain gets much worse then definitely get it looked at - it may have got trapped out of position. You may be able to gently relocate it on your own when the surrounding soft tissue relaxes but do try to take it easy as it'll be more prone to injury for a little while. You have my sympathy, when my jaw goes the pain seems to be in the centre of your head! 8O
Stone
