Worried first time duck mum!

[Jennyducks]

Gladys has been to the vets twice over the past 3 weeks as I could hear her whistle breathing, the vet said he could hear some irritation but that she is lively and feathers are looking great so no need to worry yet.
The past 4 days she has list her neck feathers and the others appear to be wetter than usual which could be wet feather or could be gaps in feathers I'm guessing?
I have inspected and seen black specs but nothing moving and that could be mud as she has made a mud bath atm and is enjoying it!
She is eating, running, foraging all day but has started resting more than her sister this morning.
I'm guessing the vet will say come in but he didn't seem to experienced and was wondering if anyone here may have some experience with the same thing?
Diet is nutritional yeast, waterfowl finisher, peas, foraging, mealworm all daily.
Thank you in advance for any advice!

 

[AshVau22]

How old is she?

 

[Jennyducks]

How old is she?

11 weeks

 

[AshVau22]

Does she have access to daily clean water? Have you noticed anything different in her preening behavior? She could possibly be a clogged or dirty preen gland. The whistling breathing I'm unsure about if it's been 3 weeks your hearing it and it's not progressing to running nose or watery eyes then I'm not sure. Hopefully some more experience duck peeps respond. I've only once had a duck with a clogged gland.

 

[Jennyducks]

Does she have access to daily clean water? Have you noticed anything different in her preening behavior? She could possibly be a clogged or dirty preen gland. The whistling breathing I'm unsure about if it's been 3 weeks your hearing it and it's not progressing to running nose or watery eyes then I'm not sure. Hopefully some more experience duck peeps respond. I've only once had a duck with a clogged gland.

I have noticed her preening her neck a lot more, they have a large water bowl to dunk their heads that is cleaned daily and the pool is emptied and brushed every othet days.
Thank you I'll research the gland now, I was concerned with her behaviour this morning as she was standing up but resting her head in her wings but no other symptoms like runny nose etc.
I've brought them in for a rest and to dry off for now!