3yo ds fell off the bed last night and landed on his bottom.
Cried a lot. Went to bed. Woke regularly to complain of pain in his bottom.
Woke up this morning unable to weight bear and complaining of a sore ear. Took him straight to A&E.
The whole time we were at hosp he was giggling and fine. Did a bit of fake limping for the doc but then giggled, stumbled and caught himself perfectly, no pain in his leg. Climbed on to the hospital bed to better demonstrate his fake limp.
Thorough examination. Absolutely fine. Not a squeak or complaint when the doc was seriously manipulating and poking his leg and spine.
Left the hosp walking fine but when we got to nursery his symptoms mysteriously reappeared. Unable to weight bear, crying, clingy, everything "owey".
So I took him home. With a face like this: 
Okay, so obv faking but maybe it is a bit bruised and he had a terrible night so no point in leaving a sad, clingy boy at nursery.
The thing is he has kept it up all day. And it is a bit too sophisticated for him to have managed tbh: He woke up on the sofa, saw his sister watching his fave cartoon, leapt off the sofa to race over and his leg buckled and he cried because it hurt and he needed to be carried.
He has insisted on being carried everywhere, but he can walk fine on it and it doesn't seem to hurt him when he does. But if I say no, you can walk he will stay where he is and cry rather than walk to where we are which is NOT him at all. Even when we are doing something exciting in another room he will stay where he is rather than walk there. HE is only just 3 and simply doesn't have that self control.
That's long sorry. Any thoughts?
(He is happily playing with his sis atm. He's not acting like a sick or in pain child at all).