Both resistant RI and IBD can make the others snakes Ill without mites. If you have any inkling that it could be either of these you need to keep that one particular animal as far away from the others as possible. Is possible to transfer it from contact with you from one snake to another. Please be as careful as possible. Ive never dealt with either though and both scare the crap out of me bc it's heartbreaking to see something you love in pain and not be able to help it. And there's not much factual info on either. The only thing you can do is wait and see and protect your other animals. There's peoples experiences with both and what vets have seen in necropsies. I know one of the true blue signs of IBD is a RIs that don't go away, as well as star gazing and poor locomotion control (movement and muscles) I've seen many YouTube videos on IBD and it's quite sad. I went though the same with a rescue I took in last year that has a head tilt and odd movements occasionally. But I've chalked it up to a trauma, or overheat left untreated. She was in qt for 6 months though. I'll never really know her true issue though. The problem with taking in rescues especially is we don't know what they come in contact with before us. IBD kills balls especially quickly and horribly though and the fact she was sick right off is pretty scary. I don't know the actual timeframe with balls though. I'm
Sorry I can't give you 100% answers. Possibly take a video of her actions and get it up here so others that may have had experience with either of these diseases can look at it and see. For now just be as careful as possible especially avoiding all contact with the others snakes. Do her last, no reusing food, utensils, avoid contact with her mucus, feces, wash hands immediatly, try grabbing some latex disposable gloves to use on her and throw away immediatly. I'm sorry I know this doesn't help much. But if by chance this is either hopefully this will be an isolated case. I will be hopeful in that its not either.
Morgan