Duck with runny nose

[Rooka_2]

Oh boy do I seem to be having duck problems... I had a little duck die on me, she wasn't growing at all, she was 6 weeks old and still looked like a tiny chick. She died, so I decided to get my healthy duck a new friend. Today my healthy duck has a runny nose? Every time I pick her up white mucus comes out of her nose, she will shake and water just goes everywhere.
What could this be from? She just started sleeping outside two nights ago and she did get into some medicated chick starter food. Could either of those be the cause? Can I fix this? I'm totally new to ducks and just learning as I go along.
This is so stressful!

 

[Miss Lydia]

What are your outside temps? can this duckling get in to water at night? Medicated feed will not hurt your duckling.
https://www.backyardchickens.com/th...dicated-feed-the-myths-and-the-truth.1247838/
Hows the appetite and energy? eyes runny?