Ducklings have lump on foot - bumblefoot or normal?

[Nefelibata]

My ducklings have been having some balance issues. I recently noticed some small lumps on their "heels". (both ducks are in this picture, these feet are not both the same duck)
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They are khaki campbell ducklings, a little over two weeks old.
I noticed the bump when I first got them (the 25th), but thought it was normal.
Both ducklings have this small lump on each foot.
They have no other signs of injury except their wobbly-ness, and I have no idea what could have caused it.
They have been eating starter kibble mixed with oats and brewer yeast, as well as lettuce and peas.
Their poop seems normal, runny if they've been eating a lot of peas and water.
I thought the wobbly-ness was a niacin deficiency, so I've been adding supplements to their food and water.
I want to know if this is an issue, and if so, what I should do about it. I am 100% willing to take them to the vet if necessary.

 

[Show Sebright]

Is it the fleshy area in the center of the feet??? Like a Palm on a human hand. Yes so that is perfectly normal. Well if it is kinda squishy and not hard.

 

[Isaac 0]

Could we see a video of them walking around so we can gauge how off-balance they really are? To post a video, upload it to youtube or Vimeo, and copy/paste the link here.