Yeh, as Jo suggests, it sounds like a typical respiratory infection... Is the discharge in her eye reddish? If so, then it's porphyrin and is secreted from the eyes and nose during times of stress or illness, don't worry too much about it, just keep it clean if there's a lot, but she'll most probably be washing it off herself (if she is still cleaning there'll be some on her hands where she's wiped it off)
So yes, don't stress about the discharge, just take her to the vets and get her on some meds... hopefully it will just be a minor infection and nothing growing there that's compressing her lungs and it should clear up after a short while on baytril which is a standard rat antibiotic... Also, if she seems quite distressed use only fleece or towelling as her bedding rather than shavings, just to clear the air of dust and help ease her breathing.
Keep us updated on the little sweetie x
