Friend of mine fell off on The Slab at Gisburn on Good Friday and bent his thumb back. Apparently there’s a “plate” on the back of the thumb (second bone, not the scaphoid) that’s there to stop the thumb bending back. If you take it too far this breaks. He ended up in a special cast to stop the thumb bending backwards after surgery to sort it out. He’s still wearing the cast to ride….
I think you’re risking alot here youth. Get yourself to a hospital!!!!!!