Strange behaviour with pet duck

[Gingernutt]

I have a pet duck and he's about 3 years old now. Yesterday he was perfectly fine and normal but today he is acting very off, unsteady balance, sometimes goes into upward posture, walking backwards and aggression which he's never been aggressive before. Not sure what the issue is he has no access to anything toxic or metal, he has the appropriate diet with enough niacin. He is drinking, eating and popping fine.

I have attached a video of him in a clothes basket to monitor him, he is alittle wet as he did slash around in water.

 

[Gingernutt]

https://jumpshare.com/s/XdDTkGtPuKqshFBr2qql

 

[Jenbirdee]

The video is not accessible to me. Can you upload it to YouTube and then post the link?
What is your set up like is he an indoor duck and outdoor duck in a secure run? How can you be sure he has not had access to any metal sometimes things work their way up from underground.
What kind of food and water bowls are you using anything metal zinc poisoning can cause instability.
But I would like to see the video if you can try posting it a different way