Your vet should do bloodwork and xrays. At her age this could be cancer, it is unlikely that a simple URI would take her this long to get over. Has she been in contact with other cats lately? Has she ever been tested for feleuk or FIV?
Originally Posted by sunnicat
When I first started reading this thread, I was so worried! It does sound as if Lucy is improving, which I hope is still the case. You have done an amazing thing, caring for this girl the way you have. Rest assured, she will never forget the love and kindness you have shown her!