Thanks, guys. Well I did manage to get some sleep at last (though not as much as I'd have liked!) I think I must have eaten something that disagreed, because I'm not in a flare, and haven't had this particular pain before.
Little miss- it doesn't hurt when I press or anything like that. Breathing makes it worse if I'm lying on my right, but not when I'm on my left so I don't think it's anything too serious.