By no means am I an expert, but I'll go ahead and give you my thoughts. First off I hope you have different anitbiotics than the first course. What was she on for the first RI and for how long? How long has she been off the meds? It sounds like the other antibiotics didn't do much, or not enough. I think the vets are able to do cultures of the bacterica and determine which antibiotic will be most effective. I would talk to your vet about possibly doing this. It sounds like you have a very seriously ill snake. (make sure she's not anywhere close to any other herps!!) I wish I could be more help, but hopefully someone else will chime in here soon.