How is she this morning? If you feel comfortable vomiting, do so this morning. I only like to vomit once in the morning so that during the day they can absorb water and food. The stuff in the crop right now is pretty toxic and they do feel better getting it out of there.
She isn't contagious and doesn't need to be kept separate, however don't let her get to any hard foods the others might be eating. We don't want to slow the crop waiting on the gizzard to grind hard foods, we need food to move as fast as possible. Soft foods today and until the crop moves normally.
If you can get get some Acidified Copper Sulfate today, get that going. It will help to combat a few things along with the sour crop and help greatly. Skip the mineral oil but the vaginal cream can't hurt either.
Keep this program up for a week, she should start to improve in a few days. If not, we may need to try other things like worming or cocci meds.
Keep us posted!