If this baby has not yet had a lactation evaluation, you may be able to give her some wonderful suggestions for latching.  Babies who give their mothers sore nipples through nipple shields should be checked for anatomical abnormalities...like tongue, jaw and palate issues.  We know this baby had a tongue tie that was cut by his father so it may not be resolved.  In my recent experience with both anterior and posterior tongue tie releases done by professionals, mothers and babies often continue having problems with painful latch and sore nipples, slow weight gain and plugged ducts.  Frenotomy revision has always worked, often with dramatic positive results.  (One of my mothers was a surgical Physicians Assistant and considered doing it herself but chickened out.)  All of these mother-babies are now breastfeeding normally.
It does sound like these nipples need immediate healing and working with her to find a reasonable alternative method of feeding would be ideal.  I would imagine that hand expression, cup or bottle feeding might be preferable until the nipple heals enough to use a manual or electric pump...or at least until the revision is performed and baby can return to the breast without causing further damage.  Linda Dahl, a NYC ENT gives post-operative instructions to her clients to push up the bottom of the baby's tongue several times daily after the frenotomy to prevent the open area from healing on itself and sealing over again.  
CST is invaluable for these babies, too, since this one has already been using his tongue this way for 4 weeks.   Breastmilk expressed and allowed to air dry on infected nipples can be very healing, as well as medi-honey if she is opposed to mupirocin or APNO.  If they are infected, it is a good idea to soak them in bowls of warm water several times a day after expressing milk but before applying breastmilk or medi-honey as a salve.
I would also evaluate this baby's weight gain with the WHO chart and mother's supply because 4 weeks with a tongue tied baby on a nipple shield will undoubtedly have lowered her production.  Baby may need more than what mom can produce at this time.
Annie Brown, Family Nurse Practitioner, IBCLC
Greenwich, CT

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