Abdominal pain, night sweats, racing pulse, inability to eat, short of breath. Why can I not get anti-MRSA antibiotic?

In the last 24 months I have had 2 separate 10 day antibiotic courses for MRSA , then a total bowel clean-out for a colonoscopy after that then 3 days of penicillin for what turned out to be MRSA in my throat then just 5 days of a ten day course of anti-MRSA antibiotic. Nine days later I started having abdominal pain, night sweats , racing pulse and an inability to eat. 54 days later I am still very ill, I have lost 30lbs from 176 to 146 and my height went from 5 10.5 to 5 9 all in those 54 days. I have tested negative for C-Diff and the MDs(except a gastroenterologist who said I either I had C-Diff or Systemic MRSA) cannot seem to conclude I have Systemic MRSA in my GI tract and possibly my lungs since I am short of breath 24/7. Why can t I get a strong anti-MRSA antibiotic until a get a fecal transfusion (which was recommended by the last gastro MD). Please advise