I finally had my GI consult today.

C. difficile is not the only bad bacteria. There are a bunch of them. Yeast (like from vaginal infections and thrush in the mouth) is also one.

I'd see what your OB thinks about taking the antibiotic. If she's hesitant, or if I felt hesitant, then I would do the probiotic thing until the baby is born, then see the GI again a couple of months afterwards (give your hormones time to straighten out) if I was still having problems, then do the antibiotic.

While on the antibiotic, and for a while afterwards, you should take probiotics. While the next antibiotic dose will kill the good bacteria you just put in, studies have shown that people on probiotics while taking antibiotics have less diarrhea (because antibiotics cause diarrhea all on their own). I have certainly found this to be true in my case. You have to continue to take them after you get off the antibiotics to make sure that you get your guts repopulated with the good stuff, or the bad stuff can easily take over again. For a week's antibiotics, I continue probiotics for a week to three weeks afterwards. For a month's antibiotics, I would stay on probiotics for 1-3 months after stopping the antibiotic. And since I do dairy products, even after stopping the probiotics I would drink acidophillus milk and consume yogurt as wanted; that's a light, but constant update to your good bacteria.

One thing about the high fiber diet and fiber supplements. I am one of a few weird people (some others on here) that get worse when I get into fiber. Weirdest thing, but one fiber supplement made me more constipated when I took it, and when I had D, it made that worse too. I was never bold enough to try another fiber supplement. Especially not after I ate some blue corn chips and got diarrhea. I eat yellow/white corn chips all the time with no problem. The only thing I could see is that the blue corn chips are like massively full of fiber. So too much fiber appears not to agree with me. You may be normal and get better bowel movements with the introduction of fiber, but if you notice a sudden change for the worse, stop it. You may be weird like me.

Flagyl is an extremely strong antibiotic. There have been a few people come through here (Sarita for one has taken it MANY times) and everyone has felt pretty crappy while on it. Pun very much intended. Flagyl is notorious for making people feel nauseous and have lots of D. I would definitely hold off until you talk to your OB.
No matter what you decide to do, you should difinitely consider probiotics right away. I don't even have a bacterial problem and I take at least 2 versions of it a day. It has kept my IBS in check for a couple years now. Probiotic pills are wonderfully efficient, so are yogurts and milks.

<<I forgot to mention, he suggested the probiotic "for life." I think I also forgot to mention (in my post) that I had strep in September of 2007 and took a traditional course of amox, which is what he thinks triggered my problems, even though I didn't notice the change until November. >>

I read up on this a few years back when I suspected a round of antibiotics had triggered a bad bout of diarrhea in me. It's called antibiotic-associated colitis, if you want to look it up. If your D is caused by just not enough good bacteria, then probiotics for a month or so could have you right as rain again. If it's bad bacteria in there, then the probiotics might not help at all, might help some, or, if taken long enough, might correct the problem. If they don't help at all or enough, then you'll have to combine it with antibiotics.