Actually, carpal tunnel syndrome is 'common' in pregnant women, so
breastfeeding may have just exacerbated this.  I see a lot of moms who hold
their wrist in awkward positions. The best position is with the wrist very
slightly extended (5degrees)and the hand in  what is called neutral position.
A generic wrist support that can be purchased at a drug store may help, but
if she has not already seen a professional, an orthodpedist appt. is called
for. Carpal tunnel can get very nasty, and like any orthopedic problem, early
treatment is better than later. I learned that the hard way. When my third
child was very small I tore my rotator cuff muscle from carrying him in a
sling (with incorrect posture) too much, but negelected treatment until he
was almost three, when it was too late to do anything but operate to remove
the calcifications.  As an OTR/CLC, I love seeing and helping women who have
physical challanges to  breastfeed.  The best bet is to find an OT in your
community who is breastfeeding friendly- keep looking until you find her(or
him).

Debbie Rabin, OTR, CLC