Your poor babies. I hope they return to normal soon and that it was just a case of nerves. Otherwise, I would visit your vet, of course.
You can give 2-3 teaspoons, generally. There is always a risk that it may not agree with the pups, depending on their systems and diets.
This is from when Max had a serious bout of constipation and gas:
http://www.yorkietalk.com/forums/sic...-possibly.html
This post specifically:
http://www.yorkietalk.com/forums/2982762-post4.html