I would just leave him be, with minimal handling(only handle when cleaning the enclosure). Wait until a week after all of the injections are finished(as he is more prone to regurgitation at this time because the antibiotics are killing off the bad and the good bacteria) and then try to feed him a very small meal(hopper mouse or rat fuzzy).

What is his setup like right now? How are his temps and humidity and how are you measuring these? For your temps, I would aim for(and maintain at 24/7) 94-95 warm side and 84-85 cool side, with 55-65% humidity.

Setting him up in a small tub would be a good idea right now as winter just saps the humidity out of glass enclosures(not to mention, glass isn't a good insulator and you probably have wild temp swings-not good for any snake). I would go to WalMart and get a 27-32qt tub(or smaller depending on how big he is) that is about 6" high. In my snakes' tubs that aren't in a rack, I have newspaper as the substrate, a small water bowl, and two small identical hides.

Good luck with him, hopefully he can get over this infection quickly.