I hope your cat is better by now, our cat was diagnosed with cat flu a few weeks back (she was a stray who adopted us) the vet was hopeful that she'd make a good recovery, she was very poorly, runny nose, cough, lethargic, off her food etc. She received antibiotic and steroid injections every day for 3 days and was given some pain killers and then a course of oral tablets, thankfully she has made a full recovery but the vet says she'll always be a carrier. It's worse in burmese cats because of their short respiratory tract.