Soak that snake. Every other day at least. Antibiotics are hard on their kidneys, and they need those extra fluids. I had several animals shipped to me last year with RIs, and it's par for the course. If your vet is telling you not to soak, I'd find another vet.

If you're almost done with your course of antibiotics and see no change, I'd drag her back in for something else. Sometimes it can take months of battling and several switches of meds before you finally kick an ri, just hang in there.