Breathing problem, possible mites, need a clean out

[CocoPopz]

I currently have a flock of 12, 4 silkies, 2 speckled, Rhode Island Red and 5 cross breeds (1 is a cockerel). Long story really, I'll start with there breathing.
For a while now I've noticed they make a weird noise when they breathe, there noses aren't clean, sometimes they look like they've had recent mucus, but the shed they are in isn't brilliant for ventilation, so I'm guessing, well I know that's the reason as when I've added other hens to the shed they soon got the bad breathing, they're not bad to the point where they're breathing out there mouth but when they breathe in, basically I'd say it's like the common cold? But my amazing new shed which I can assure you has enough ventilation should be up over the weekend, I don't know if it's worth putting them on some kind of antibiotic to help clear it up, so they have a fresh start in the new shed? If so, do you know any antibiotic I can get hold of in the UK which should clear it up if there is some kind of infection in there .
SECOND...I think they're getting scaly leg mite again, but last time I didn't buy any proper stuff for it, now I was just wondering if anyone has any advise on that, to get rid o any if there is, as well as some kind of treatment I can put on the chickens that kills any kind of parasite they might be carrying before I transfer them to my new shed, I've checked them and I can't see anything, just think its worth putting something on encase? I also don't know what people views on are about giving them a good bath? Is that actually possible? If so can someone please help me out?
1) treatment for breathing problem
2) scaly leg mite treatment
3). An overall treatment for mites and lice to treat them with encase?
4) stages to bath, if that's even normal?
Basically I just want a clean start in my new shed! I have mite cleaner what I clean the shed with but nothing directly for the chicken, just so you know I live in the UK, thanks x

 

[Yorkshire Coop]

I'm sure you can't get antibiotics without vet prescription. Scaly leg mite can be treated by putting Vaseline on the legs after spraying with suitable leg mite killer. I would try to keep them out doors as much as pos to get fresh air. If you have red mite in your shed that could be causing breathing problems mite poo is like a grey dust. I would give the birds a good dusting with louse/ mite powder before moving them. Not sure on bathing never done mine. Good luck with your move into new shed hope they settle in well and are better soon.https://www.backyardchickens.com/a/clinical-signs-for-common-respiratory-diseases-of-poultry. https://www.backyardchickens.com/a/mites-lice-treatment-and-prevention

 

[TinyBirds]

I don't know what products you have in the uk, but if you were here I'd say use tylan injectable for the breathing, and a drop of neem oil applied just above the vent and also a drop behind the neck will kill lice. For mites you either dust them with sulfur powder or bathe them in a bath of 2 ounces sulfur powder per gallon of soapy water. Then a few days later dust them again. For the scaly leg mites sulfur is again a great thing to kill mites, mixed with Vaseline or similar. For really bad cases I've heard people dip the feet in gasoline. Whatever is used on the parasites, just make sure to do several applications about 5-7 days apart to bee sure and kill the new generation as they mature before they lay again.

 

[CocoPopz]

Thank you so mucH, that's helped a lot x