I've been watching this hoping someone would post a suggestion, but why couldn't you just feed him some plain whole yogurt? The cultures would probably be just as active, but then again, I'm not a vet (nor do I pretend to be) so hopefully someone who has alot of experience with this stuff will answer.
I know yogurt fixes steers with acidosis, and they usually give them humongous probiotic pills for that...
I guess I'll continue eating popcorn (don't I wish haha)
I would highly recommend Bio-K. It has the most live cultures of any probiotics. You can get it at Whole Foods and it'll be cheaper than that (and more effective!). I give it to my pets, children..and myself of course.