I don't see how it can be the muscle thing, surely it would hurt, or at least feel like how it does just after you've given birth, y'know when you cough, and you feel like you have to hold your belly, to stop it exploding or something? And it isn't sore or tender at all.
Moosma, I hope you are right in your little prediction, but I honestly feel about as pregnant as a coffee table at the moment, but then I didn't feel pregnant with DS2 or the MC either. (I did with DS1 for some reason, but then, DS1's and DS2's pregnancies were very different)
I just keep going around in cirles, one minute I'm convinced I am pregnant, the next I am worrying what else it is, Oh well, only another day or so to go...!