Siamese coughing

I suppose I am looking for support in the case of my sons landlords young Siamese cat(5yrs old)he's one of 4 cats.
He has actually been coughing for about a year,but the last time I saw him,it seems to be getting worse.
I drove them to a vet(owner has no car)a couple of months back,she was very casual about the problem,gave him some antibiotics and told the owner to put Visine:confused: in the cats nose.
He did not get any better,is actually worse,to me,the cough comes from his chest has nothing to do with his sinuses,but I am not a vet.
The owner thinks it's allergies to small feathers from his new Parrot(he has 2),could that be a possibility??

I've offered to drive them to his original vet(who has moved),but I'd like to have some ideas of what this dry coughing could be all about,it's not hairballs.
Any ideas?
Here he is..

Coughing can be caused from many different things such as heart conditions, allergies, and asthma and parasites. I attached a link that discusses this and if you look at the bottom of page 2 and onto page three it discusses Chronic Bronchopulmonary disease which is common in Siamese.

Let us know if the vet finds anything.


http://www.felineasthma.org/Coughing.pdf

thank's L4H,I am sending it to him:thumbs up