Hope he makes a full recovery.

If you can monitor the temps though that would really be beneficial in his aid to fight the infection.

With the infection so far down into his lungs, I hope he's able to fight it off.

You COULD ask your vet about using Fortaz as well, it's an antibiotic that's good for a bacteria known as anaerobes which would multiply deep down in the lower oxygenated parts of his lung.