Karen, I have just finished working with a similar mom as your mom whose baby
lost weight. The mom I worked with had good days of breastfeeding but then
would get busy with the extremely demanding 5 yr old then wouldn't nurse as
well and the supply would go down, she wouldn't be able to pump as much and
didn't feel the let down. This baby lost alot of weight and the mother didn't
even recognize the signs, she thought the sunken eyes made the baby look
alert!  I found out in talking with her she thought some of the baby's cries
were for attention and not for feedings. It took alot of convincing that this
mom needed to stop all other activities and concentrate on the baby. She used
the SNS to build up the milk supply again Had her work closely with doctor
and follow drs directions exactly. The baby is now 4 mos old and is doing
great and is completely bf.. What I learned from this case was to really
listen to all the factors involved in the nursing situation, what is the
family like, what are the mothers perceptions about the baby etc.  While a
drug may increase milk supply the real problem is the family dynamics and
getting the mother to realize what needs to be done for bf to succeed. The
other thing I learned was not to take the mothers word for how the baby
looks. Go and see with a home visit. Your mom seems to need alot of support,
even daily support, in order for this to succeed.
I hope sharing this situation helps. I know it is not a direct answer to your
question about syntocinon. I believe that your mom's milk supply will come
back with frequent and proper nursing sessions.
Kathy Ford, LLL Leader, Harveys Lake< PA