Baytril should work and usually is the best (imo) for respiratory illnesses.
However I find it is best given as a shot, not orally. Over 14 years ago, I had some chins with respiratory infections from their previous breeder's home. I lost the first one who had it - because I was too late in giving the meds to him. The others I caught on quick, gave them baytril, handfed them food with a syringe, and within 2 weeks, they were back to themselves. Only lost one other chin (a baby), after using the baytril.
Orally, I find it is hard, as the chins do not like the taste too much (some even seem to push it out with their tongues, LOL.) and it seems the shots tend to work much faster.
The only thing with the shots is sometimes they can be left with scabs from it, if you're not too careful. If you're not familiar with giving shots, you might see if your vet can do it for you, if you pop in there twice a day for it? Just a thought. My vet showed me how to administer them, and from others I know with similar respiratory problems in the past, their vets showed them how to, as well and their chins turned out fine.
The dosing seems okay that you mentioned, as it should be given based on their weight(hence the difference in the amounts.). Anyhow, just thought to mention about my experience with baytril and respiratory issues.