Jacinta,
You'll find that there's always a strong reaction against live feeding becuase it is so risky. But let's move past that. What's important is your sick snake.
Snakes are tough little blighters so good to hear you're not giving up on him yet. What did your vet say about any future antibiotic shots? Do you know what kind of antibiotic he used? The betadine is a good idea. Did the vet say to use it straight or dilute it?
There are a few people on here who have extensive experience with sick and injured reptiles and should be able to offer advice. In the meantime, what are your snake's enclosure temperatures like?
EDIT: Someone beat me to the temperature question.