Sounds like your hen had sour crop, a fungal infection caused by yeast growing in her crop. The same condition can also be brought about by a bacterial infection.If this happens again Best thing to dois to try to get her to eat some live-culture yogurt, to get some good bacteria started in there. Then, either take her (or a swab of her throat, taken by wiping the back of her throat with a swab and putting that in a sterile syringe case) to the vet to have a gram stain done of her crop. If the results show a fungal infection, she will need to be put on nystatin at a dose of 1 ml/350 g body weight, twice a day, orally. If the results are bacterial, baytril is the best drug to fight off bacterial infections, especially those involving the digestive tract. This can be given at a dose of between 10 and 15 mg/kg, twice a day, orally. Good idea to put a bird on baytril AND nystatin, if the test results show a bacterial infection, as a fungal infection usually comes on as a result of the baytril killing all the bacteria in the crop, allowing an overgrowth of Candida yeast.
If there is no vet available to do a gram stain immediately, then try to get ahold of some grapefruit seed extract and give her 1 drop, dissolved in 10 cc water- give this by syringe orally. GSE is an effective antifungal and antibacterial, but don't give it at the same time as the yogurt or both will be "deactivated". Give the yogurt at least an hour after the Nystatin, baytril or GSE.
If the results come back negative for a bacterial or fungal infection, chances are she has something else more sinister going on in her that is causing the crop to become sluggish. Check to make sure the crop isn't overfilled and/or impacted. Also, check her abdomen (or have your vet check it) to see if it is swollen. Check her weight- does her keel stick out or is it still relatively "meaty" on both sides of it? A sluggish crop will result if a bird is suffering from cancer or any other disease that is taking its toll on the body...
Hope this helps a bit