The vet I go to uses Fortaz instead of Baytril, she said it covers a wider range. Often a vet will take a shot with a broad antibiotic like this before doing a culture. Snakes tend to get sick slow and get better slow as well so make sure you give your snake the full amount of shots as the vet instructed. If this doesn't fix the issue you can have the vet do a culture and figure out exactly what the problem and solution is. This will cost around $100 on top of the next prescription. I wrote a thread on my experience with using an over the counter product called Tylan 200 after Fortaz did nothing. It cleared the RI after 3 shots, but my situation was probably unique.