My blue orp has an odd squawk and a runny nose and is breathing slightly heavy

[Sire12]

She started making these weird loud "caws" one at a time, I first noticed it a month ago but didn't think much of it since she's been eating, drinking, laying, just doing everything normal but today I picked her up and noticed one of her nostrils was runny and I could hear her breathing, which I can't really her with my other girls, everyone else is laying and dust bathing and seem happy enough too so could she possibly have a respiratory infection? If so what's the best medicine in the UK to treat it? Also if it matters I dosed them all recently with vermx wormer and gave them all 2 drops of ivermectin behind the neck she got 3 drops because she's a huge girl, they also get fermented grain and acv in their water

 

[Sire12]

Ok I've sat with her a while she only seems to do the loud squawk when she is eating it sort of reminds me of someone trying to eat with a blocked nose I think it's definately a respiratory infection does anyone know the best type of medicine in the UK that I can ask the vet for

 

[The Chickens' Maid]

The loud squawk is probably a chicken sneeze. That's what my girls do when they have something blocking their breathing. As for medication, usually for "cold" symptoms like this, I would just give a general antibiotic that's meant for birds. I'm not sure where you'd find that in the UK, but in the US antibiotic for barn fowl is usually available in farm/agriculture stores in dosages for whole flocks (or dosage per gallon of water).