janet,
im not sure what specific bacteria ferment lactose, i think many do. you can try taking a probiotic, but watch out for bad reactions. you could have a short term herx reaction which is a good thing, but some have reported problems with all probiotics. for "normal" people, probiotics are a good thing. you need these bacteria. however, for those who have messed up guts and immune systems, they may cause problems. if you do not experience a bad reaction, it is probably a good thing to take a probiotic.
flaring with dairy could be due to the lactose or just plain old food sensitivity. i know of people who had part of their intestines removed and can no longer tolerate lactose. i think this is because without parts of their intestines, there is no bacteria to ferment the lactose
