The vet isn't sure what it is. Not grass or obstruction. Until yesterday she was eating, now she isn't interested. Any suggestions as to what this can be? She is on antibiotics.

I can assume that your vet listened to her heart for any murmurs? Heartworm is the one thing that really jumps out at me. What sort of testing has already been done?

She listened to her heart, was fine, Temperature was normal. She detected a little more of a problem her left lung, but nothing serious. I am not sure how long it will take for the antibiotics, the cough suppressant and one other, to start to take effect. I suppose I am a worried mum! We are waiting to see if the medications start to ease her symptoms. The next step, I suppose is blood work and x rays. Kennel cough was ruled out. Thanks for your prompt reply.

So, was the vet thinking lung infection?

No,

Has the vet given you any idea of what he was thinking?

Maybe Pneumonia?

She listened to her heart, was fine, Temperature was normal. She detected a little more of a problem her left lung, but nothing serious. I am not sure how long it will take for the antibiotics, the cough suppressant and one other, to start to take effect. I suppose I am a worried mum! we are waiting to see if the medications start to ease her symptoms. The next step, I suppose is blood work and x rays. kennel cough was ruled out. Thanks for your prompt reply.

Was there a negative heart worm test?
Another possibility, polyps or some sort of irritant in the airway, by irritant I'm thinking more along the lines of some sort of twig or other small things that could be inhaled and work further into the airway.