I feel for you because Izzy is exactly the same. We went to the vets yesterday and he suggested, as i had done anyway, upping his Frusicare. He seems fine during the day but coughs during thet night, in a very shrill way, whereas before, he only coughed first thinga dna couple of times a day and very briefly.
I've been sleeping downstairs with him, as he usually comes upstairs with us, but I felt that , like with me, the cold night air was making him cough.
We don't have the central heating on , as it suits neither of us and, in fact , ubntil the weekend, he seemrd to be thriving on the cooler weather.
Another thing was that his eyes went sort of horizontal and puffy round the membrane surrounding the socket. Fran's boy has been off too and he had bad eyes, though her vet treated for infection and mine reckonned (it had cleared up when we saw him) that the swelling was probably due to extra hard coughing.
Let's hope these boys are just having the temporary effects of this odd foggy weather and that it will soon clear up.
Barbara, Monty, Joly and Teddy.