Why don't you put her back with her flock.
Feel of her crop when she goes to roost at night (dusk), don't put any food or water in their housing at all at night. Then go out and feel of her crop again first thing before you give her food and water.
If the crop has emptied by morning, there's nothing to worry about.
Do provide your chicks with grit (crushed granite).
If you are massaging and manipulating the crop when she's been eating and drinking, then she's going to be adjusting and stretching her neck. Chickens do not have a gag reflex, likely you are pushing the contents of the crop up and around, so she's readjusting it.