c-diff, false negatives, and the wrong antibiotics?

I know there are many c-diff posts, but I didn't want to "hi-jack" someone else's post...

I have tested negatively for C-Diff twice in the last two weeks.

I was put on Xifaxan because my doc didn't know what else to do with me, and a burst of Prednisone starting at 20mg.

Since starting Xifaxan 38 hours ago:
my fevers are worse
my diarrhea is worse
my pain is worse
and to top it all off...

my bm's suddenly smell up the entire house (abnormal for me!)

AND the stupid little pamphlet that comes with the Xifaxan specifically says NOT to use if you suspect C-Diff. Well. I suspect C-Diff still, but my doc obviously doesn't.

Could the Xifaxan be making this worse? C-Diff experts, what would you do? I can demand a third test I guess?

My doc is useless at this point, and I'm waiting to go in for a second opinion, so I'm kind of past the whole "call your doctor" phase. He'll just ell me to go to the ER, again. You guys know the routine. Your 2 cents are much appreciated!

Yes, false negatives are totally par for the course. The test is so unreliable that they made me do 4 tests before that would release me from the hospital. My GI basically doesn't even bother testing me for the recurrances half the time now when I get sick because I can tell from my symptoms more reliably than from any test.
I don't know anthing about xifaxan, but certain anti-biotics do have the potential to make c.diff, so I would be wary of it, especially due to the note in the packet. And fever, pain, diarhhea, and abnormal BM smell would all be getting worse if it is c.diff.
What does your doctor think is going on that needs to be treated with xifixan? Since flagyl is used fairly frequently in Crohn's anyway AND can treat c. diff, can't you try a course of that?
If your condition continues to deteriorate, and your doctor is no help, I would recommend going to the ER. If you have c diff they'll put you on IV flagyl and vancomycin and it will wipe it out pretty quick.