
Poor baby :(
I agree with Jackie H, it's impossible to diagnose anything on the net.
however Lungworm is very rare.
I'd think it's also unlikely to be a heart condition, your vet would have listened to the pups heart. & should have picked up any potential problem there.
There is a lot of KC around at present - especially for this time of year :(
I would think it's KC, If it is, he'll be rough for a while but he'll shake it off.
There's not much more you can do other than follow your vets advise & keep him away from other dogs.