[chairman]

It looks like you fed the snake two rabbits in one sitting. That could have been an appropriate amount of food given the weight of the snake compared to the weight of the rabbits, but it could be too much. Snakes will regurgitate food if they're spooked by something and they're easier to spook when full.

Additionally, antibiotics are not used to treat parasites. If the vet really gave the snake antibiotics for a potential parasite load instead of giving meds for parasites then you might want to rethink your opinion of the vet. Unless the vet thought the parasites caused a bacterial infection, but...

... really, back to what Aaron said. You need some cultures and similar tests run to figure out exactly what is going on. There's no point in antibiotics if there's no bacterial infection and you need to know which parasites you're dealing with to know which kinds of medications will work on that variety of parasite.

Beyond that, keep double-checking the temperatures, humidity, etc, and have a vet do their thing.