Hi Marylandbob,
Sorry to hear that Xifaxan has stopped effectively treating SIBO for you. You should talk to your GI and consider a dual treatment of Xifaxan + oral neomycin, for example, for two weeks or longer, to really get on top of things. In addition, talk to your doctor about a strategy to avoid the recurrence of SIBO if possible, like pro-kinetic agents. Good luck.