If she seems o.k. to return to the flock, then I'd let her out with them, you can always pull her out to give medication/treatment.
I never withhold food/water for any type of crop issue. I just go out and treat them while in the coop or grab them and take them aside for a few minutes.
I would not vomit her.
Take care when massaging a crop that is full of fluid/water, you risk them aspirating.
Is she pooping?
If she's not, then I'd work on getting some extra Calcium into her.
You can find Calcium Citrate with D3 in the vitamin aisle of stores like Walmart, CVS, etc...