Drake limping, heel of foot warm and swollen

[cheezenkwackers]

I came home from being out of town for a couple days and my 3 month old drake is limping. When I checked him, the heel of his foot is warm, soft and swollen. I do not see any scabs, so am I right to think it is not bumblefoot? A sprain? I am about to fill the tub for an Epsom salt bath. Any other ideas?

 

[cheezenkwackers]

Here is his good foot for comparison:

 

[cheezenkwackers]

He is now in the tub and I can see his whole ankle is swollen. @Miss Lydia @casportpony