hi , my twin-sister has a gland problem right now in her arm-pit. she said it appeared yesterday, kinda like little hard ball in the arm-pit. she had it earlier, too and saw the doctor and got medicine creme and put it on the problematic place and it disappeared. well, it appeared yesterday and she put the creme again and she says it got smaller. doctor told her that it was sweat gland problem and she shouldn't use deodorant or certain type of it. well, i'm not in the same country and also i'm still nervous and want to understand what else can cause it and can it be anything dangerous. it's not i don't trust the doctor but i want to understand more.