I Have Had Diarrhea For 1.5 Years, Have Had Every

I have had diarrhea for 1.5 years, have had every test imaginable from both the VA and an outside GI specialist. The latter wanted me to take viberzi but I cannot afford it and it is not in the VA formulary. The May 27, 2015 FDA release approved both viberzi and Rifaximin for IBS-D. The VA has sent me the rifaximin but I'm not sure I should take it. I do not have any abdominal pain, just loose stools 24/7. What do you think?