I have never seen RI in a beardie. I have seen lots of rescue snakes with ri. Oral treatment should be fine. The thing I question is 10 days. Reptiles have slow metabolisms and it usually takes 10 days to start working. I would expect to see 30 days in a snake anyway. Also my vet very very rarely uses baytril anymore as many bacteria are resistant to it and it is only gram negative bacteria. Did the vet do a culture? This is the best way to resolve the best drug to use. Sadly they typically are not as useful after a round on antibiotics.
You might PM skiploader and seek his insight.