Is the eye swollen and an unpleasant smell coming from the nostrils? If so, this sounds like Mycoplasma. Having very recently had experience of Myco (last week) a visit to the vets is essential - to get a proper diagnosis and antibiotics if necessary. Unfortunately, once a bird contracts it, it cannot be got rid of just made to lie dormant and will re-surface at times of stress to your hens. It is also contagious (passed through air borne virus or by shared drinking vessels), so you need to quarantine her until you can get her to the vet and be very careful about bio-security until you are sure - especially if you have young birds, which can be more susceptible to the virus. I brought Myco into my flock last year and since then have had several outbreaks of it and in my experience, hens that contract it don't usually thrive. I've now invested in a giant bottle of soluble Tylan, so that the minute symptoms appear, the affected hen is isolated and dosed with antibiotic. The good thing is Tylan works very quickly and a great improvement can be seen within 12 hours.