he can dunk his head in a heated dog bowl too it just isn't as tall as a bucket but if you think he's able to stand up to a bucket get him one. I use heated dog bowl inside on days like today and heated buckets outside. we're at 14 so I have birds that won't come out till it's up into the 20s...
As long as he’s eating that’s important. There are on line places for antibiotics but unless you think he has a sinus infection I wouldn’t put him on any.
Do you think he may have a sinus infection? have you tried him on antibiotics at all? I think that's a good idea wrapping his leg maybe it will give him enough stability that he will walk better to plus protect his skin from breaking down. Poor boy. Is he eating good? Yes his feathers will grow...
You can keep straw under the liner as long as you can keep it dry. Just with all that going on with him I wouldn't think laying on wet bedding will help.
To correct his foot and keep it from curling you could make a little shoe for him or buy duck shoes which can teach him to lay his foot flat again. I'm sorry Are you letting him run around with the rest of the flock? you'll have to watch his wings that he doesn't wear the feathers off an get sores.
I can't imagine the Terramycin causing this since it's an ointment. Maybe the discharge from his eyes caused the gunk to harden. You know how if a child has a bad cold and they eyes are affected the eyes can get gunk hardened until the eyes mat closed. Maybe that's what has happened. I'd try...