Aye, mine's very similar.
Quite a while ago, (in september?), when i was using rimjam blues ((N)), i went to roll to the edge of a curb, and they slipped, so i landed horribly, sideways on my ankle, and sprained it very badly. (Pics somewhere :P)
I let it heal pretty much, and was fine, untill about a month and a half ago, i rolled off this 1 foot drop, landed it with my foot too far backwards, so jolted it upwards. It was only a very minor sprain, and so i was fine to ride, but every so often, whenever i did something, and landed it ever so slightly wrong, (like you), i would be in agony for like 5 mins, but then be fine.
Then i did what you can see in my other topic, which luckily was a very minor sprain, but one of the guys we were staying with is an osteopath, so he had a fiddle, and after lots of stretching, and far too much cracking, seems to have fixed it all. So i'm gonna see if it still "twings" when i ride. (Y)
Best bet, try an osteopath. :)
Mike.