I'm really chuffed you used the name Boing, I've never had the chance to name a chick before He/she is absolutely beautiful. I really hope your other chicks are doing better now.
I'm in the UK and probably no help whatsoever, but your post touched me. Sorry your Mum won't help you but you obviously care very much.
All I can suggest is that the wing is kept still and supported in it's normal position (maybe a search on here for a similar injury will help), and that your...