Grace,
What I have to offer is an anecdote of one case.  Baby had bloody stools for a
few weeks on 100% breastfeeding, but was happy and gaining well.  As I recall
he was under six months but not a newborn.  Mom had eliminated dairy products
from her diet without any improvement in the problem.  When she eliminated
beef as well, based on advice from calling Ruth Lawrence's hot line, the
bloody stools stopped.

I think you are right to be cautious about a GI person who thinks formula
would be a better choice than working on the mother's diet.  The search for "a
GI person who knows something about breastfeeding" could be a long one!!!

There was a pediatric GI doc (and breastfeeding mom) who spoke at LLLI last
summer.  Who on Lacnet can supply her name?  Maryelle Vonlanthen is as close
as my memory can come.

Best wishes.    Chris Mulford