I suffer with this myself all winter and have found that it is not only
foods that cause it.  The biggest culprit in my life is the furnace.  As
soon as the furnace turns on and the humidity in the house goes down I
have a problem.  We run vaporizers in the house all winter and it helps a
bunch.  Another major contributor to these problems is the "soap" you wash
the infant with.  The liquid baby soaps are very irritating to some skins.
 Suggest that she use a beauty bar with lotion on the baby.  Be sure she
isn't using baby wipes.  They are very drying.  No dryer sheets, if she is
using a soap powder recommended for infant laundry try the other one, or
switch to regular powder.  In our area "I----" doesn't rinse out of the
laundry well due to the acidity of our water.  Lots of babies get the
dreaded rash from the clothes that carry this build-up.  I have talked to
many women with babies with these problems over the years, both breast and
bottle babies.  Soy and milk based formulas seem equally guilty of
contributing to the problem and most babies do better on the more
expensive stuff if they are formula fed.  I have also found that strange
things have helped this problem, like eliminating apples (juice, sauce,
and whole) or strawberries from the mom's diet.  I had a run on Sweet
potato and Squash reactions in infants diet several years ago.  I have
seen an infant rash up with oatmeal.  I would suggest going back to Rice
Cereal, if Mom insists that Jr. needs it, and only breastmilk and formula.
 Give it a week to see if there is any change-if not take away the formula
or change the type.  I would encourage her to stop the formula but it
sounds like "she" needs it.

I try to remember when talking to a mom with these problems that she goes
home and deals with it all while I go home and will talk to her again in
the morning.  Some of the things that we know would lead to a better
chance of resolution are easier said than done.  When I am tempted to list
in desending order the 8 things I think would help resolve this issue to a
stressed mom I try to put myself back to 1974, twin premies with medical
problems, a stressed out two year old, a husband who flies around the
world at the beck and call of the Air Force-who would have issued him a
family if they thought he needed one-and well-meaning relatives 900 miles
away but possessing all the answers. I find that listing some of the
obvious things and asking her which she can deal with first puts her in
charge and gives her the space to make some decisions. Good luck!