u/BeneficialComplex469

3-4 week old chick open-mouth breathing, wobbling, clicking sounds, slight vomiting/regurgitation — anyone know what this could be?

Hi everyone, I’m really worried about one of my chicks and hoping someone has experience with this.

It’s about 3–4 weeks old and started acting strange recently. Symptoms include:

-repeatedly opening its beak/open-mouth breathing AFTER it eats and has a full crop, when it’s crop is empty it doesn’t do the beak thing but it’s still unstable and struggles to walk

-occasional clicking sound when breathing
wet nostril at times

-wobbling/weak legs (possible splay leg issues too)
-sometimes falls over or struggles walking
-keeps wanting to eat and still has interest in food
-crop was empty earlier but now eating mushy crumbles
-slight regurgitation/vomiting just now
-breathing involves lifting head up/down sometimes

No diarrhea, neck twisting, or other sick chicks. It’s currently separated from the others.

I did use a VERY diluted flea spray (Elector PSP) on a q-tip around the coop/chick area several days ago and now I’m paranoid maybe irritation/exposure contributed somehow. I treated it and its siblings five days before it started to show the symptoms. Its siblings are fine and healthy.

I attached a video/photo of the breathing/open-mouth behavior. Has anyone seen this before or know what this sounds like? Respiratory infection? Aspiration? Crop issue? Neurological?
Any advice appreciated. I’m trying to keep it warm, upright, and hydrated without force feeding.