Injured Duck

[RiversideMeadow]

Hi there, I recently purchased a flock of ducks (Pekings, Rouens, Buff and Cayugas). When I got the flock home, I noticed one poor little fellow was hurt. On further inspection, both of his "ankles" are swelled a bit and scabby. His tail is tucked under him. He stumbles when he walks, using his wings to help balance him on the ground. He is eating and drinking but is understandably nervous when we approach him (or her.....it's a Peking duck and I can't tell them apart yet lol). The other ducks were picking on him a little, so I placed him in a container with shavings and fresh water to drink away from the other ducks. I thought it might help if he stays off his feet for a bit until I can get him cleaned up and see what I can do for him. Any ideas of what it could be? I am thinking he might have a case of frostbite in them. Any help would be appreciated.