I agree. I have found that we need very high levels of probiotics, especially after abx. I also give a "normal" dose during abx. For an example we use Klaire Labs Complete 1/4 teaspoon is 100+ billion CFUs. Maybe 1 x 1/4 every day and if I see there is an issue I have done 4 x 1/4 to try to get back on track.
I buy as bulk (not in capsules) to get it a little cheaper. I also use saccharomyces boulardii separately - almost daily - to keep back yeast. Klaire Labs has a lot of info on their website about probiotics.