Thanks Freedom, Denise and Deb.

I took Tiger to the vet and they took xrays of his chest and lungs. The vet showed them to me and said there is definitely something going on with the left side of his lung field. There is this milky haze to it and some small white spots, maybe 3 of them, about the size of half an apple seed. She said that if the cancer had metastisized she would have expected to see large spots that would be tumours but she can't be sure what the small spots are and she thinks they could be a number of things.
I left Tiger with them for about 2 hours and she said that in that time she was really able to hear how gurgly he is in his chest and alot of noise coming from his nasal area as well.
The vet said it is not pneumonia but she thinks he could be dealing with inflammation of his lung air sacs and there may be some fluid around his lungs. This could either be due to the cancer or from an infection that doesn't respond to the antibiotic Convenia injections he's been getting. If it is an infection, the only way to be sure what kind of bacteria it is would involve a culture of the area which is way too invasive and she doesn't want to go that route. Neither do I. And I'm sure Tiger would agree!

So, what we decided was to give him a Depo Medrol (spelling??) injection yesterday, (steroid) and if it is inflammation from the cancer, the xrays that will be repeated next week should show some improvement. If so, then we will continue with Depo shots every 2 weeks as palliative care to make him comfortable.
If there is no improvement, then it is likely a bacteria infection and we can begin to try some antibiotics and hopefully will find the right one sooner rather than later.

I expected that he would be doing much better this morning but he is exactly the same. In the past, when he has received a Depo shot, the results would kick in within an hour and last for days. But this time there is no change so far so I think it might be an infection after all.

I think this is potentially good news in that his breathing difficulties of late may be due to an infection that is hopefully treatable.

I'll keep ya posted.