You really can’t go wrong with the Kirkman’s Pro-Bio Gold. It’s likely one of the best available. It’s a good multistrain probiotic that is completely dairy and soy free. For children under 30 lbs it is recommended to give 1/2 capsule per day. Some kids with more severe GI problems may need more (like my little Paige).
Some kids may actually show worsening of GI symptoms initially when starting a probiotic. This is OK – it’s a sign that the “bad” bacteria, yeast, etc. is dying off as it is being outcrowded by the “good” bacteria in the probiotic. These die-off symptoms could be irritability, gas, cramping, diarrhea, etc. and usually only last about a few days.