Peekin chick breathing issues

[Ducks of westshire]

First time duck owner, couple of my ducklings are mouth breathing short and fast breaths, no nasal discharge but this is my first time so I'm a nervous wreck. my assumption is an upper respiratory infection and a product called vet rx could help. I'm not sure so here's a video of my lil buddy, please let me know what you think it it.
Sincerely,
Ducks of westshire

 

[Isaac 0]

Welcome to BYC.
Excluding the panting, do the ducklings seem to be acting ok, if not, please elucidate?
Could you take a video of them panting, upload it to a video platform such as youtube or Vimeo, and copy/paste the link here?
Do the ducklings have access to head deep water?
What is the temperature in their pen area?

Respiratory issues in ducklings are most often associated with an excessively high temperature in the brooder; when the temp may seem low, if their birds are close to each other, simply the heat there giving off can cause them to pant. A large brooder allows birds to regulate whether they want to be under the heat source provided or not.