Pullet with two huge lumps by hock

I have a pullet who was fine one day and then in the evening was having trouble walking. When I examined her she had two huge lumps- one on each side of her hock, and they were quite sensitive. I've separated her from the others, as she can't walk, and been soaking her in Epsom salts each day… Giving her electrolytes and vitamins. The soaking she seems to enjoy, and it does lessen the swelling, but after four days the lumps remain.

I've looked at pictures of Merrick's disease and that's not what it is, there is no lesions or head on the lumps. I was thinking of lancing them but that doesn't seem exactly right. Can anyone help?