Lethargic chicken, empty crop, not eating.

[minichickiedragon]

Hello. One of my chickens, a 5 month old bantam, was standing in one spot and not moving for a while. She's normally difficult to catch but I've had no problem picking her up.
Right now she's inside in a carrier with water. She's mostly just sitting down. Crop is empty aside from a few pebbles. Not interested in eating (tried live mealworms to really entice her but no dice). I used a syringe to get her to drink a bit of water, like a few ml worth.
Vent is not obstructed/puffy. Didn't feel an egg/mass in her when I checked her stomach/rear. Hasn't gone to the bathroom since I took her in. She doesn't have any discharge or discoloration or weird breathing.
I have a small number of birds and the rest are doing fine.
Can anybody please help with identifying what's going on?

 

[Eggcessive]

Has she started laying? How often, and when was last egg? Could she be egg bound? Is her tail position up or down? Is her comb red? Can you mix some water in a small amount of chicken crumbles or pellets and make a mush, then offer that with a little scrambled egg to her beak. Any pictures of her or her next dropping could be helpful.