Ah, okay.
Could you describe it in detail? Does it seem disorientated, unbalanced, does it favour a leg or limp? Does it fall backwards, to the side, or is it able to walk okay?
I think trying niacin is the way to go
But I would perhaps also get some nutri drench to supplement as well. Gives...
I don't think that's the correct thing, being in the UK you'll need to use the niacin capsules instead
Niacin capsules
These work well. 50mg per gallon is the dosage, available 24/7 in waterer. Along with brewers yeast, 1 or 1.5 tbsp per cup of feed.
Are you able to post a video of the...
@Dawn powell it isn't the correct form of niacin, that is no flush, which is a slow release form- you need flush effect which is fast release.
B complex would be better though, if you can get some, tractor supply should sell it, it's the Durvet brand. 1 ml orally via a treat, daily.
Brewers...
I don't trust that diagnosis.
The wobbling to me sounds like a nutritional issue or neurological. I would not give up on treating him, but if we're to give advice, we need to see the baby in a video
Is this a crested duckling by any chance?