I take Nature's Way Primadophilus. It's got L. acidophilus and a couple other yummies. It does have a huge amount of live cultures, more than any other brand I've found. I take 4-6 a day but most people can get by on 1-3.
Can you give us a list of every single medication/supplement you're on? You've had a ton of tests done, including a liver biopsy, so it's possible the pain/discomfort could be something as simple as gas pains (which can be very uncomfortable). You say you have diarrhea but are taking lactulose for constipation; which is more predominant for you?