Muscovy Injured and Not Eating

I have a 2 year old Muscovy Drake who i found sitting outside his pen three days ago, unable to walk.
I brought him inside into a box straight away, checked him out but couldn't see any obvious breaks or injury. He could bare weight on his left leg but nothing at all on right. Fell straight down as soon as he went to take a step.
None of my other drakes had ruffled feathers (checked them thinking a possible fight) so the cause is still unknown.
I didnt expect him to eat straight away due to the stress of it all but its day 3 now and he's still off his food (id guess a handfull of feed in the time he's been inside). Still pooping & drinking though. Ive had him in the bath today to check the leg out a bit better, ive got movement on the right leg now (swimming, extending it back & forward) but he cant flatten it out (like when standing on it) and still doesnt seem to be able to hold his own weight. left leg is all good.
I dont really know where to go from here, im happy for him to be inside and to continue with the water therapy but im really concerned about him being off his food. And off course the inability to walk. Should he be able to bear weight on the leg by now, would i know for sure by looking if it were broken?
Any advice much appreciated =)

 

Hi there, my boy died yesterday.
He had been ran over by the neigbour and had internal injuries.
Thanks for the duck forum link, i've been on BYC many times but first time as a member, was a bit confused as to where to post.