BAd thing about Tylan is its works on a bacteria known as Mycoplasma.
Respiratory infections arent generally caused by this in snakes, but more so in rats.
In my research and in dealing with Respiratory Infections, Tylan would be the drug I would try after the other major drugs failed, such as Amikacin, Enrofloxacin, Fortaz, even Ciprofloxacin, etc etc
You need to get to a vet and get a Culture and Sensitivity test performed to determine what to use.