I have a ball python and two burmese, every once in a while one of them will go without eating but not for more then 1 week at a time. It could quite well be going through a slow shedding process, adiquate climate helps out in the shedding process. Here are my two suggestions for you, spray all the walls down daily with water to add some more humidity to the cage, or what I actually will do is put mine in the shower at least once a month. The shower really helps with the shedding. I usually get the water luke warm and turn them loose in there. They seam to love it, I can actually turn the shower on and the snakes will go to the shower on their own. I take it your freeding them frozen? You may try to switch to a live rat for a feeding, sometimes snakes are pretty picky.