AIf they're taking this well, a syringe or too of plain water will help too.
Otherwise, if you
can't get to a vet, or even if you can
just have to keep doing this and hope he rides it out.
If it's having trouble breathing, there's something you can buy at any pharmacy called "Gentle vapors". It's a plug in thing (light socket) that you use for babies that emits menthol. We put a few in the bathroom (has to be a small room), ran the shower on hot, and left it plugged in.