So ds has been demonstrating his disgusting skill of creating 'wings' with his shoulder blades - essentially he can make them appear out of his back, so much so you can hold them. The others can't do this.
I started thinking.
The other day one of the kids was complaining about a weird finger thing the same ds was doing, which was clicking and dislocating his fingers.
He hates handwriting, cries, mains, sobs etc.
Is this hypermobility? He also sits oddly with legs the 'wrong' way.