Dcat (9 yo) has had recurring flu since she was a tiny kitten (rescue). It flares up when she's stressed and subsides with the help of antibiotics.
She has recently beaten injection site sarcoma and been declared 'cured' by her specialist, which I am obviously thrilled about as the odds weren't great.
Predictably though, the stress of surgery and radiotherapy have made the cat flu come back. This time it won't go away despite three rounds of different antibiotics and anti-inflammatories. Her breathing is noisy and her nose completely blocked on one side. It is especially bad at night, and when she's sleeping.
The vet says the only option now is steroids or 'just leave it'. 
Does anyone have any experience of treating chronic cat flu any other way? I'm a bit reluctant to put her on steroids, but I need to do something as it is clearly annoying her. A friend suggested echinacea; I'm pretty sceptical about homeopathy but have reached the point where I'll try anything - she's a very special cat.