Just got back from the vet.
Although we couldn't get a sample from him, the vet said that it could be an infection so she's given me a weeks worth of antibiotics to see if he improves. If not, it could be senility.

She also said that it could actually be a combination of both. If it is a combo, I'll only see a little improvment..but at least that's something.
So we'll see how we go with the meds. Plus, now I've got to try and get a sample from my tiny guy. LOL Oh what fun!
She also listened to his heart and he has a strong murmur on both sides.

She wasn't sure it had anything to do with his problem but it is probably the reason he occasionally coughs.
She did say that she thinks the heart murmur has been there a while and isn't causing him any problems so isn't that big a deal...but we'll have to wait and see. She's going to check it out more thoroughly when we go back next wednesday. So, fingers crossed.
However, she said that overall he's very healthy and active for his age and has an excellent coat.

At least that's something good.
Thanks for all the postive thoughts guys. It's much appreciated.
Cass.