I just had a quick look in other forum posts about probiotics for babies and the one that's reccomended is baby biotics.

Here's a post from Kelly on the topic....
A naturopath would have far greater access to decent probiotics - Nicole Tracy the BB naturopath is brilliant and based in a few locations, East Melbourne and Park Orchards. Some members were talking about this in another thread about babies getting sick alot, I think they recommended Baby Biotics? Or something like that. Hopefully one of them will post but its a cold winters night on a Sunday, you might have to wait a little for a reply! You could also get Fast Tract which is a bit more exxy but very potent and organic, gluten free. They deliver very fast. Great for the whole family.

And here's some product info...
BioCeuticals - Baby Biotic 0+ yrs

Baby Biotic 0+ yrs

BabyBiotic 0+yrs® is a dairy-free probiotic supplement specifically designed to help maintain healthy digestive function in neonates, infants and children. It may assist in the management of allergies, provide relief from the symptoms of eczema, and strengthen gastrointestinal immunity. BabyBiotic 0+yrs® combines Bifidobacterium breve, B. lactis and B. bifidum - three of the most common species of bifidobacteria present in the gastrointestinal tract (GIT) of healthy breastfed newborns and infants.

You may be able to buy it online or over the counter at a health food shop that stocks the BioCeuticals range. You may need a naturopathic script for it though but I recon Its well worth it.
Good luck, lets us know how you go.