Just took back a clelia rustica that I sold two years ago. Owner was one of those people we often meet in the hobby that dove feet first into oddball snakes and then decided after about 6 years that it wasn't for her.
Anyway, upon picking him up, I noticed a solid slug of phlegm coming out of the glottis and bubbly breathing.
In the last 18 months I have become a huge fan of nebulizing. I had done it several years ago on an anthill python, but have become a bigger advocate of it recently.
I have an igloo cooler with drain plug on the bottom. The output nozzle of the nebulizer fits neatly into the drain plug hole. I line the bottom of the cooler with substrate and I'm set to go.
40 minutes in the cooler once per day for 10 days usually does the trick. I have found that if the situation is dire enough (as it was for this clelia), that in lieu of waiting on a culture I will have the vet give a double or triple non-contraindictive antibiotic dose to start, then nebulize with the targeted antibiotic when the culture comes back.
A good nebulizer to get is the Evo Vet Neb Express.
FWIW the nebulizer/cooler combo also can serve as a shed aid for bad sheds. Just use straight distilled water.