Karen,
Perhaps mom's letdown is now getting really established - i.e. forceful.
 Maybe measures for oversupply, overactive letdown would help.  I have saved
many tips on overactive & oversupply -  e-mail me if you want them.  Or what
about birth control pills or shots - can reduce supply.
Otherwise, look for illness in baby - ear, throat, thrush, UTI, whatever.
Laurie Wheeler, rnc, mn,ibclc
louisiana