I hope you will find good probiotics for your son. I do use some of them too, and Elaine Gottschall which is the Mother of the SCD Diet says that there are some probiotics that helps the intestines better than other and some that you absolutely should avoid cause they could make more problems than help. Here are the good ones: Lactobacillus Bulgaricus, Streptococcus Thermophilus and Lactobacillus Acidophilus. She says that we have to avoid Bifidobacterium Bifidus, but to be sure, avoid all that has a name with Bifidobacterium first....
At her website, www.scdiet.com you may read a lot of interesting things about how she did her research to help her daughter which had IBD, and how she has helped a lot of people with Crohns all over the world. The diet craves a lot of work from the implicated, but it's a great pay off.
Yoghurt is excellence, the best yoghurt to use is the one you'll read about at Elaines pages, you make it your self at home, and you add probiotics in it as a yoghurt starter. This prosess makes the yoghurt almost lactose free, and it will throughout a fermentation going on for 24 hours be filled with a lot of probiotics! So the home made yoghurt will be a natural immunsystem booster with all it's good and right probiotics. Other yoghurt that u buy in the stores contains a lot of sugar and lactose, and it's better to avoid those stuff.
You don't have to choose to go for all the diet, or maybe chose another diet for your son, but, the yoghurt will be of great help for his health. If you decide to use a common yoghurt for your son....maybe u could find one without sugar and with some good probiotic strains.
I have bought a yoghurtmachine, I make my own yoghurt and it's really delicious! I add blueberrys and ripe banana, and it's tasting sweet - really yummy
With all the best to you and your son,
From Ingrid in Norway