I was misdiagnosed with UC when I really had c-diff. I insisted on a c-diff test, though my doctor thought that was certainly not necessary as I was an otherwise healthy adult. I was put on pred and went on vacation, only to get a call that, yes, I was positive for c-diff, so I took Flagyl (and took Flagyl again, and finally got rid of the sucker with Vanco).
I would not at all be surprised that you still have c-diff. It is quite common to get a false negative, but you will never get a false positive. Since Vancomycin is so very expensive, and it is a drug of last resort, I would see how your symptoms are over the next few days to a week and/or insist on a stool test, and if you felt you still had your c-diff, I'd take the vanco. It will probably take care of the c-diff problem.
I was hoping that with this diagnosis, I did not have UC after all. Unfortunately, a year later or so, I was diagnosed with UC and now take Azathioprine every day to treat it (quite successfully, I might add).
Good luck to you!
Sporadic proctitis since about 1985. Mother had J-pouch surgery 1983.
DX'd with clostridium difficile in 2000. Pred, two courses of Flagyl, then Vancomycin finally got rid of it. 2001 colonoscopy dx'd left-sided UC. . Treated with prednisone, Rowasa, Asacol. Asacol not working, switched to Imuran. Three small flares since in 2002, 2005, and 2007, brought under control with steroid and Rowasa enemas. Lap Chole performed October 26, 2007, after gall bladder attack in June, '07.
Daily meds: 100 mg Azathioprine and 225 mg Effexor XR (for chronic, longstanding depression), many vitamins and Primadophilus Reuteri