Sharon -
I believe Maryelle is a pediatric gastroenterologist and hopefully will reply
to you in better detail than I.
In the meantime my husband is an adult gastroenterologist, but we live in a
rural area and he is often called in on peds consults.  (Or I consult with
him on one of my LLL calls.)  It's become quite a fad here to attribute any
fussiness to "lactose intolerance" in the baby.  The peds advise the moms to
give lactaid drops directly to the baby after each nursing session.  They are
NOT approved for oral use!
My husband says that lactose intolerance is probably the most under-diagnosed
illness in adults and most over diagnosed illness in infants.  Most adults
are lactose intolerant.  Adults are not meant to drink milk.  Only northern
Europeans and the Masai - dairy herding cultures - retain the lactase enzyme.
 All other people begin losing it about age 6 (is that the natural age for
weaning?) and become increasingly lactose intolerant as they grow older.
 However virtually all babies DO have lactase and are NOT lactose intolerant.
 They might have a reaction to the cow's milk protein from the mom's diet.
I think we as a culture have a very low tolerance for normal baby fussiness
and normal baby gas.  It's not a disease!  I advise mom's re comfort measures
for the babe and make sure it's not a foremilk/hindmilk imbalance (which does
not sound like an issue in this case.)
Good luck!
Cynthia