it sounds like she knows a bit about BFing & hopefully she's on top of the mastitis - if she needs to go to the doctor could you offer to drive her/help look after her other two?

what about taking her some snacks/meals? i know one of the hardest meals for me at first (and this was with only one baby ) was lunch. i had a couple of people bring me dinners but i found i spent so long on the couch during the day that i never got around to making myself lunch & i was so HUNGRY!