Jen, I had a long chat with Dr. Kocen at SouthPaws about this subject when Mandy had a couple of back-to-back (no pun intended) rounds of stomach issues.
He told me that most of the protocols involved performing multiple 3-day fecal checks, but that most of the literature he has read advises that even with doing that, false negatives were common and to just give a full treatment of Panacur. I did so and it made a difference. I believe (it's been about 5 years now, so my memory is a bit dim) we did Panacur for 7 days. Her diarrhea pre-treatment was intermittent, but when it was bad, it was BAD.
I would wonder, however, if maybe she's sensitive to chicken. I know another adopter from our group has a dog that had recurring intermittent issues (she was feeding raw as well) and when chicken was completely cut out, she stopped having issues. Interestingly, that dog doesn't have issues with turkey.
The other thing you might try is Vibrant Pets. I know several dogs that have done well with it.
By the way, I was told that only a tiny amount was required for a fecal, however I would just bring in the whole "deposit".
I hope Faith feels better soon!