I'm so sorry. I know what it's like to have the docs just attribute some abnormality to being your child's "baseline." A lot of times, that means, "I don't know." So, I'm all for finding someone who DOES know!
Glad you decided to get a second opinion. I think that you should have asked the doc if he would have liked having diarrhea for his whole life, minus 6 weeks. You can bet he'd have been trying to get his 50th opinion.
(((HUGS)))