Bumble foot, HELP!

2 days ago I purchased 3 five week old ducklings and they all looked fine then this morning I noticed they all had bumble foot seemingly overnight! They haven’t been near anything sharp or anything like that and I’m not sure what to do! I’ve treated bumble foot on my chickens but I don’t know how to do it with ducks. There aren’t any vets near me that see ducks. I’m trying to use drawing salve to fix it but I don’t know if that will help. What should I do?