Can cats have colds?

Question
Dear Dr. Schiavone-Brensinger,
My cat has sneezed all her life (about 6 years).  Lately that sneezing has worsened, so I took her to the vet.  He did a chest xray that was clear, and ran a cbc that also returned normal.  So, he put her on prednisone.  That was 10 days ago.  Now, her nose is so congested that she really can't breath out of it at all without trying to blow out the congestion.  Most of the time the congestion is clear, however every once in a while she blows a chunk of something.  
Our vet said that if the prednisone didn't work then it was probably a growth, and she would need to have a scope of her nose.  
Is it possible that she just has a cold, or a virus?  If so, what question should I ask the vet?  I am really looking for a second opinion.  Can you help?

Answer
Hi Jennifer!  My first and foremost possible diagnosis would be that your cat has an upper respiratory infection, therefore making me firmly believe that the prednisone prescription (which is a steroid) should have been an amoxi prescription (an antibiotic).  
If there was a growth of some sort, that would have been seen on the x-ray.
When you mentioned that the nasal discharge is usually clear, but occasionally she blows a chunk of something...what does this chunk look like?  If it is green...this is absolutely and most definitely an upper respiratory infection.  If it is blood, a bloody discharge can be due to the irritation in the nasal passageway from an upper respiratory infection, or it could indicate a foreign body, like a mass in the nasal passageway.  If it is bloody discharge you are seeing occasionally, if it was a mass, the platelet count on the CBC should have been low.
My suggestion?  For tonight or tomorrow, stick her in the bathroom with you while you take a hot shower, with the door closed.  The steam from the shower will help decongest her a bit.  Next...give your veterinarian a call and talk to him about this.  If this is an infection, it's important to treat it promptly with antibiotics before it turns into pneumonia.  If this is due to a growth in the nasal passage, treatment is also important promptly, as being this congested is not only a health hazzard, it's highly uncomfortable for her!
At this point, from what you have told me, I would definitely be leaning toward an upper respiratory infection as a diagnosis.
I hope this helps, and if you have time, please keep me posted!
Sending tons of get well purrs to your kitty!
Hilary