Sinusitis treatment without antibiotics?

[KayTee]

Hello, I've just joined the forum because I bought three point of lay chooks about 3 weeks ago. Up until now they've been fine, but three or four days ago when I let them out I heard the grey one (I don't know what breed they are - they were sold to me by colour!) making a really weird gurgling sound. She seemed ok during the day, and I've only heard the noise very occasionally since, but today I've noticed that one side of her face is slightly swollen, particularly behind the eye. She's running around the garden with the other two, eating, drinking and pooping well, although she tends to sit around a bit more than the others. (Could just be her breed / nature?) Looking at pictures taken last week, I can see that even then it was already starting - you can see the lack of feathers around the swollen area. Neither of the other two are showing any symptoms. I'm posting pictures of both sides of her face taken today, to show the difference. My big problem is that I live in France, and antibiotics are only available with a vet's prescription. Does anyone have any reassuring words or advice - does this look like something that needs treatment, and if so are antibiotics the only way? I hope that I'm just being a paranoid newbie, but I want to do the best for my girls, and don't want to let them suffer.
In case it's important information - I have a commercial hen-house (rabbit hutch style - not very big, but roomy enough for the 3 girls), lined with newspaper under the perch (changed daily) and straw in the nest boxes (changed weekly). She occasionally sleeps in the nest box, but is getting the hang of using the perch each night. She's not started laying yet.

Thanks for any advice you can give!

Right side - looks normal





Left side - swollen

 

[rosebuds]

it will not hurt to put a little antibotic around the eye and where it is swelled.