usually when you first pick up your pig, they will be extremely fearful. i take it you took her directly from her mother?
just put your place in that piggies shoes (or little feet) and imagine her situation. she's no longer with mommy and she's in a new cage she isn't used to.
it'll take her a while, just leave food near her and leave her be. don't try to touch her if she happens to venture out of the hut or around the cage.
you could break the quarantine if you strongly believe she needs to be around other guinea pigs. honestly, that could be it, but keep in mind most new pigs take a while to adjust.
also, if you think she came from a very healthy home, then she could have no health problems, but prepare to pay for a vet bill if she does pass something to your pigs.
i think if you're truly worried and she isn't touching her food or water, you may want to consider introducing her to the other pigs to see if her fear subsides. once again, prepare for vet bills, however i believe the young pig's life is more important than money.
when i got my second pig, i quarantined her for a bit, but i rarely saw her eat and the water level in her bottle never seemed to budge. i feared she could die of water or food deprivation, so i introduced her to my other guinea pig. she was a totally different pig after meeting my other pig. she was eating, drinking, and popcorning. luckily, my new pig didn't infect my other pig, so i'm very happy i made the decision to break the quarantine.