jeane,
I also experienced butt burn and that anal fire sensation the last couple days before I gave up on VSL#3 DS, in addition to the other symptoms. No bleeding though.
I plan to hang on to my VSL#3 DS supply and take a packet between antibiotic dosages for the reason you suggested: as an anti c-diff measure. However, I have never had c-diff despite being an involuntary antibiotic "abuser" for almost 20 years now. I don't know if that is due to luck, or having diligently rotated all antibiotics I have taken.