Was it a F/T mouse that you didn't thaw all the way? Was it maybe bad? I've read about issues with a certain rodent company(i'll keep the name anonymous) that had bad F/T and a few people had the same symptoms as you got but their snakes regurgitated the food item in an acidic extremely foul smelling pile. Regardless though, bottom line is you need to get the snake to a vet. I've fed my snakes stuff that was too large before but all they did was go into a food coma for about a week longer than usual for obvious reasons but after that, they were back out and looking for dinner again.